Television
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"TV" redirects here. For other uses, see TV (disambiguation).
For the band, see Television (band).
Braun HF 1, Germany, 1959
Braun HF 1, Germany, 1959
Clivia II FER858A (VEB Rafena, Radeberg, Germany), 1956
Clivia II FER858A (VEB Rafena, Radeberg, Germany), 1956

Television (often abbreviated to TV) is a widely used telecommunication system for broadcasting and receiving moving pictures and sound over a distance. The term may also be used to refer specifically to a television set, programming or television transmission. The word is derived from mixed Latin and Greek roots, meaning "far sight": Greek tele (τῆλε), far, and Latin vision, sight (from video, vis- to see, or to view in the first person).

Since it first became commercially available from the late 1930s, the television set has become a common household communications device in homes and institutions, particularly in the First World, as a source of entertainment and news. Since the 1970s, video recordings on VCR tapes and later, digital playback systems such as DVDs, have enabled the television to be used to view recorded movies and other programs.

A television system may be made up of multiple components, so a screen which lacks an internal tuner to receive the broadcast signals is called a monitor rather than a television. A television may be built to receive different broadcast or video formats, such as high-definition television, commonly referred to as HDTV. HDTV costs more than normal TV but is becoming more available.
Contents
[hide]

* 1 History
* 2 Technology
* 3 Geographical usage
* 4 Content
o 4.1 Programming
o 4.2 Funding
o 4.3 Television genres
* 5 Social aspects
* 6 Environmental aspects
* 7 References
* 8 Further reading
* 9 External links

[edit] History

Main article: History of television

[edit] Technology

Main article: Technology of television

[edit] Geographical usage

* Timeline of the introduction of television in countries

Main article: Geographical usage of television

[edit] Content

[edit] Programming

See also: Category:Television genres

Getting TV programming shown to the public can happen in many different ways. After production the next step is to market and deliver the product to whatever markets are open to using it. This typically happens on two levels:

1. Original Run or First Run – a producer creates a program of one or multiple episodes and shows it on a station or network which has either paid for the production itself or to which a license has been granted by the producers to do the same.
2. Syndication – this is the terminology rather broadly used to describe secondary programming usages (beyond original run). It includes secondary runs in the country of first issue, but also international usage which may or may not be managed by the originating producer. In many cases other companies, TV stations or individuals are engaged to do the syndication work, in other words to sell the product into the markets they are allowed to sell into by contract from the copyright holders, in most cases the producers.

First run programming is increasing on subscription services outside the U.S., but few domestically produced programs are syndicated on domestic FTA elsewhere. This practice is increasing however, generally on digital-only FTA channels, or with subscriber-only first run material appearing on FTA.

Unlike the U.S., repeat FTA screenings of a FTA network program almost only occur on that network. Also, Affiliates rarely buy or produce non-network programming that is not centred around local events.

[edit] Funding
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The examples and perspective in this section may not represent a worldwide view of the subject.
Please improve this article or discuss the issue on the talk page.

Around the globe, broadcast television is financed by either advertising, a tv licencing (a form of tax) or by subscription. To protect revenues, subscription TV channels are usually encrypted to ensure that only subscription payers receive the decryption codes to see the signal. Non-encrypted channels are known as Free to Air or FTA.


Advertising

* United States

Since inception in the U.S. in 1940, TV commercials have become one of the most effective, persuasive, and popular method of selling products of many sorts, especially consumer goods. U.S. advertising rates are determined primarily by Nielsen Ratings. The time of the day and popularity of the channel determine how much a television commercial can cost. For example, the highly popular American Idol can cost approximately $750,000 for a thirty second block of commercial time; while the same amount of time for the World Cup and the Super Bowl can cost several million dollars.

In recent years, the paid program or infomercial has become common, usually in lengths of 30 minutes or one hour. Some drug companies have even created "news" items for broadcast, paying program directors to use them.[citation needed] [1]

Some TV programs also weave advertisements into their shows, a practice begun in film and known as product placement. For example, a character could be drinking a certain kind of soda, going to a particular chain restaurant, or driving a certain make of car. (This is sometimes very subtle, where shows have vehicles provided by manufacturers for low cost, rather than wrangling them.) Sometimes a specific brand or trade mark, or music from a certain artist or group, is used. (This excludes guest appearances by artists, who perform on the show.)

* United Kingdom

The TV regulator oversees TV advertising in the United Kingdom. Its restrictions have applied since the early days of commercially funded TV. Despite this, an early TV mogul, Lew Grade, likened the broadcasting licence as a being a "licence to print money". Restrictions mean that the big three national commercial TV channels, ITV, Channel 4, and Five can show an average of only seven minutes of advertising per hour (eight minutes in the peak period). Other broadcasters must average no more than nine minutes (twelve in the peak). This means that many imported TV shows from the US have un-natural breaks where the UK company has edited out the breaks intended for US advertising. Advertisements must not be inserted in the course of any broadcast of a news or current affairs program of less than half an hour scheduled duration, or in a documentary of less than half an hour scheduled duration, or in a program for children of less than half an hour scheduled duration. Nor may advertisements be carried in a program designed and broadcast for reception in schools or in any religious service or other devotional program, or during a formal Royal ceremony or occasion. There also must be clear demarcations in time between the programs and the advertisements. The BBC, being strictly non-commercial is not allowed to show advertisements on television, the majority of its budget comes from TV licencing (see below). BBC content delivered outside of the UK such may contain advertising because those ouside the UK do not pay the licence fee.

Taxation or TV License

Television services in some countries may be funded by a television licence, a form of taxation which means advertising plays a lesser role or no role at all. For example, in the United Kingdom, and in many European countries, some channels may carry no advertising at all and some very little. The BBC carries no advertising and is funded by an annual licence paid by all households owning a television. This licence fee is set by government, but the BBC is not answerable to or controlled by government and is therefore genuinely independent. The fee also funds radio channels, transmitters and the BBC web sites.

The two main BBC TV channels are watched by almost 90 percent of the population each week and overall have 27 per cent share of total viewing despite there now being a choice of more than 40 free-to-air commercial tv channels.[2] When the same sporting event has been presented on both BBC and commercial channels, the BBC always attracts the lion's share of the audience, indicating that viewers prefer to watch TV uninterrupted by advertising.

Subscription

Some TV channels are partly funded from subscriptions and therefore the signals are encrypted before broadcast to ensure that only paying subscribers have access to the decryption codes. Some subscription services are also funded by advertising.

[edit] Television genres

Television genres include a broad range of programming types that entertain, inform, and educate viewers. The most expensive entertainment genres to produce are usually drama and dramatic miniseries. However, other genres, such as historical Western genres, may also have high production costs.

Popular entertainment genres include action-oriented shows such as police, crime, detective dramas, horror or thriller shows. As well, there are also other variants of the drama genre, such as medical dramas and daytime soap operas. Sci-fi (Science fiction) shows can fall into either the drama category or the action category, depending on whether they emphasize philosophical questions or high adventure. Comedy is a popular genre which includes sitcoms (Situation Comedy) and animated shows for the adult demographic such as Family Guy.

The least expensive forms of entertainment programming are game shows, talk shows, variety shows, and reality TV. Game shows show contestants answering questions and solving puzzles to win prizes. Talk shows feature interviews with film, television and music celebrities and public figures. Variety shows feature a range of musical performers and other entertainers such as comedians and magicians introduced by a host or Master of Ceremonies. There is some crossover between some talk shows and variety shows, because leading talk shows often feature performances by bands, singers, comedians, and other performers in between the interview segments.

Reality TV shows show "regular" people (i.e., not actors) who are facing unusual challenges or experiences, ranging from arrest by police officers (COPS) to weight loss (The Biggest Loser). A variant version of reality shows depicts celebrities doing mundane activities such as going about their everyday life (The Osbournes) or doing manual labour jobs (Simple Life).

One of the television genres, the children's and youth genre is defined by the audience, rather than by the content of the programming. Children's programming includes animated programs aimed at the child demographic, documentaries for children, and music/variety shows targeted at kids. There is overlap between the children's/youth genre and other genres, such as the educational genre.

Enable DVD and MPEG Playback In SUSE Linux Some people are having a bit of trouble getting DVD Playback to work in SUSE 10.1. Below is a tutorial that should be of some help. Although it may look like a lot of steps, everything should only take you about 10-15 minutes. This tutorial assumes that you have SUSE 10.1 installed and running. If you are in the process of installing SUSE you should make sure that you install each of the eight packages listed below during the course. If you already have SUSE installed on your system, open YaST Once you have YaST open, select "Software Management" . In Software Management search for the following programs below and just place a check mark next to them. After you have made all of your selections you may click on the Accept button to begin the install of the packages. Be sure to have your disk handy. 1. Kaffeine under "All of KDE" 2. KDEmultimedia3-video-xine under "All of KDE" 3. xine-Lib under "Gnome System" 4. xinetd under "Network and Server" 5. xine-ui under "Multimedia" 6. libdvdnav under "Gnome System" 7. libdvdread under "Gnome System" 8. wine under "Office Applications" Now, you are required to download the following packages from our website. You can use Konquer, Firefox, Mozilla or whatever you feel comfortable with . We advise you to create a folder on your desktop called dvd_appz to save the files in, that you download below. 1. libdvdcss-1.2.8-2.network.i386.rpm 2. libdvbpsi4-0.1.5-1.pm.1.i586.rpm 3. libxine1-1.1.0cvs-051002.i686.rpm 4. xine-mozilla-plugin-0.2-051004.i586.rpm 5. libmp4v2-1.4.1-3.i586.rpm 6. w32codec-0.52-1.i386.rpm 7. xvid-1.1.0-0.pm.4.i686.rpm After you have complete your download, you will need to open the Konsole Terminal . To do this, you can either click on the 3rd icon in the lower left of your screen on the taskbar or click on the start button (1st green icon on your taskbar at your lower left) then scroll up to System > Terminal > Konsole. Now we will need to log in as root. To do this you must type "su" without the quotes and hit the enter key. Next you will have to enter the root password and then press enter. Inside the Konsole screen, you will need to navigate to the folder that you stored all the downloaded rpms to. To do this, type the following without the quotes : "cd Desktop/dvd_appz" and press the enter key. "ls" and press the enter key. You will now see all 7 rpm packages listed. To install the 1st rpm, you will need to type the following without the quotes: "rpm -Uhv libdvdcss-1.2.8-2.network.i386.rpm" and press the enter key. Tip - If you type up to 9 letters and press the tab key, the rest of the command will be inserted for you. Now the system will install the package. When this is complete, you will see the following screen. After you see the above screen, you're ready to install the 2nd rpm. (Some people prefer to work with a clean screen after executing commands or installs, and if this is the case with you, you can type clear and then press enter. Then you can type ls and then press enter so that you can list the packages in the directory again). To install the 2nd rpm type the following without the quotes: "rpm -Uhv libdvbpsi4-0.1.5-1.pm.1.i586.rpm" and press the enter key. To install the 3rd rpm, you will need to type the following without quotes: "rpm -Uhv libxine1-1.1.0cvs-051002.i686.rpm" and press the enter key. To install the 4th rpm, you will need to type the following without quotes: "rpm -Uhv xine-mozilla-plugin-0.2-051004.i586.rpm" and press the enter key. To install the 5th rpm, you will need to type the following without quotes: "rpm -Uhv libmp4v2-1.4.1-3.i586.rpm" and press the enter key. To install the 6th rpm, you will need to type the following without quotes: "rpm -Uhv w32codec-0.52-1.i386.rpm" and press the enter key. To install the 7th rpm, you will need to type the following without quotes: "rpm Uhv xvid-1.1.0-0.pm.4.i686.rpm" and press the enter key. Congratulations! You just installed all the necessary packages needed to playback retail DVDs and mpeg files. To verify, simply open YaST > Software Management. Then inside the filter box, select "Installation Summary" and you will see all 7 packages. To play an mpeg file, locate the file and right-click on it with the right-mouse button. A menu wills pop-up. Now scroll down and highlight open with and select Kaffeine or Noatun or Kaboodle or xine. Any of these will work. For a Retail DVD, insert the disk into the DVD drive, a pop-up menu will open. Select "Play DVD with Kaffeine" and the movie will start. To use Xine, click on the start menu (1st green icon on the taskbar at your lower left), scroll up to Multimedia > Video Player > xine Once xine opens, insert the DVD into the drive. One of two things will happen: 1: At the pop-up menu select "Do Nothing". On the xine player click on the "DVD" tab button on the player and sit back and enjoy the movie. 2: xine will take control and start the movie automatically. By default, this action should happen. But in any event, click on the "DVD" tab button on the player and sit back and enjoy the movie. Author - Felix Cumpian Jr. Editor - Dennis Newsome 09/04/06 We would like to mention a special thanks to Felix Cumpian Jr. for his thoughthful work on this article. If you have any questions or comments about this article feel free to contact us. 09/11/06 Alternative to instructions above (submitted by Mr. Hristov - Thank you very much for your contribution!): A simple .sh file will do the trick much easier.

Below is a (non-tested version) of a file install_dvd_playback.sh

---------

#!/bin/sh
cd ~/Desktop
mkdir dvd_appz
cd dvd_appz

WEBROOT="http://www.pctech101.com/dvd_playback/files"

wget $WEBROOT/libdvdcss-1.2.8-2.network.i386.rpm
wget $WEBROOT/libdvbpsi4-0.1.5-1.pm.1.i586.rpm
wget $WEBROOT/libxine1-1.1.0cvs-051002.i686.rpm
wget $WEBROOT/xine-mozilla-plugin-0.2-051004.i586.rpm
wget $WEBROOT/libmp4v2-1.4.1-3.i586.rpm
wget $WEBROOT/w32codec-0.52-1.i386.rpm
wget $WEBROOT/xvid-1.1.0-0.pm.4.i686.rpm

sudo rpm -Uhv \
libdvdcss-1.2.8-2.network.i386.rpm \
libdvbpsi4-0.1.5-1.pm.1.i586.rpm \
libxine1-1.1.0cvs-051002.i686.rpm \
xine-mozilla-plugin-0.2-051004.i586.rpm \
libmp4v2-1.4.1-3.i586.rpm \
w32codec-0.52-1.i386.rpm \
xvid-1.1.0-0.pm.4.i686.rpm


---------

Save the file to your local disk and then execute it
$ sh ./install_dvd_playback.sh Also See: x86, x86_64, PPC - What's the difference? Playing DVD and Multimedia Files on Debian GNU/Linux

DVD From Wikipedia, the free encyclopedia Jump to: navigation, search DVD Media type: Optical disc Capacity: ~4.7 GB (single-sided single-layer), ~8.54 GB (single-sided double-layer) Read mechanism: 1350 kB/s (1×) Write mechanism: 1350 kB/s (1×) Usage: Data storage, audio, video, games DVD (also known as "Digital Versatile Disc" or "Digital Video Disc" - see Etymology) is a popular optical disc storage media format. Its main uses are video and data storage. Most DVDs are of the same dimensions as compact discs (CDs) but store more than 6 times as much data. Variations of the term DVD often describe the way data is stored on the discs: DVD-ROM has data which can only be read and not written, DVD-R and DVD+R can be written once and then functions as a DVD-ROM, and DVD-RAM, DVD-RW, or DVD+RW holds data that can be erased and thus re-written multiple times. DVD-Video and DVD-Audio discs respectively refer to properly formatted and structured video and audio content. Other types of DVD discs, including those with video content, may be referred to as DVD-Data discs. The term "DVD" is commonly misused to refer to high definition optical disc formats in general, such as Blu-ray and HD DVD. Contents [hide] 1 History 1.1 Etymology 2 DVD disc capacity 2.1 Capacity nomenclature2.2 Technology 3 Speed4 DVD recordable and rewritable5 Dual layer recording6 DVD-Video7 DVD-Audio 7.1 Security 8 Competitors and successors9 See also10 References11 External links 11.1 Official11.2 Quality guide11.3 Knowledge // [edit] History
Optical disc authoring Optical discOptical disc imageOptical disc driveAuthoring softwareRecording technologies Recording modesPacket writing
Optical media types LaserdiscCompact disc (CD): Red Book, 5.1 Music Disc, SACD, PhotoCD, CD-R, CD-ROM, CD-RW, Video CD, SVCD, CD+G, CD-Text, CD-ROM XA, CD-Extra, CD-i Bridge, CD-iMiniDiscDVD: DVD-R, DVD+R, DVD-R DL, DVD+R DL, DVD-RW, DVD+RW, DVD-RW DL, DVD+RW DL, DVD-RAM, DVD-DHD DVD: HD DVD-R, HD DVD-RW, HD DVD-RAMBlu-ray Disc (BD): BD-R, BD-REUDOUMDHolographic data storage3D optical data storageHistory of optical storage media
Standards Rainbow BooksFile systems ISO 9660 JolietRock Ridge Amiga Rock Ridge extensions El ToritoApple ISO9660 Extensions Universal Disk Format Mount Rainier In 1993, two high-density optical storage standards were being developed; one was the MultiMedia Compact Disc, backed by Philips and Sony, and the other was the Super Density disc, supported by Toshiba, Time Warner, Matsushita Electric, Hitachi, Mitsubishi Electric, Pioneer, Thomson, and JVC. IBM's president, Lou Gerstner, acting as a matchmaker, led an effort to unite the two camps behind a single standard, anticipating a repeat of the costly videotape format war between VHS and Betamax in the 1980s. Philips and Sony abandoned their MultiMedia Compact Disc and fully agreed upon Toshiba's SuperDensity Disc with only one modification, namely changing to EFMPlus modulation. EFMPlus was chosen as it has a great resilience against disc damage such as scratches and fingerprints. EFMPlus, created by Kees Immink, who also designed EFM, is 6% less efficient than the modulation technique originally used by Toshiba, which resulted in a capacity of 4.7 GB as opposed to the original 5 GB. The result was the DVD specification, finalized for the DVD movie player and DVD-ROM computer applications in December 1995.[1] In May 1997, the DVD Consortium was replaced by the DVD Forum, which is open to all other companies. [edit] Etymology "DVD" was originally used as an initialism for the unofficial term "digital video disc".[2] It was reported in 1995, at the time of the specification finalization, that the letters officially stood for "digital versatile disc" (due to non-video applications),[3] however, the text of the press release announcing the specification finalization only refers to the technology as "DVD", making no mention of what (if anything) the letters stood for.[1] A newsgroup FAQ written by Jim Taylor (a prominent figure in the industry) claims that four years later, in 1999, the DVD Forum stated that the format name was simply the three letters "DVD" and did not stand for anything.[4] The official DVD specification documents have never defined DVD. Usage in the present day varies, with "DVD", "Digital Video Disc", and "Digital Versatile Disc" being the most common. [edit] DVD disc capacity
Single layer capacity Dual/Double layer capacity Physical size GB GiB GB GiB 12 cm, single sided 4.7 4.37 8.54 7.95 12 cm, double sided 9.4 8.74 17.08 15.90 8 cm, single sided 1.4 1.30 2.6 2.42 8 cm, double sided 2.8 2.61 5.2 4.84 The 12 cm type is a standard DVD, and the 8 cm variety is known as a mini-DVD. These are the same sizes as a standard CD and a mini-CD. Note: GB here means gigabyte in the SI sense, i.e. 109 (or 1,000,000,000) bytes; while GiB is used for gibibyte, equal to 230 (or 1,073,741,824) bytes. Example: A disc with 8.54 GB capacity is equivalent to: (8.54 × 1,000,000,000) / 1,073,741,824 ≈ 7.95 GiB. Each DVD sector contains 2418 bytes of data, 2048 bytes of which are user data. Size comparison: A 12 cm Sony DVD+RW and a 19 cm pencil. Capacity Note: There is a small difference in capacity (storage space) between + and - DL DVD formats. For example, the 12 cm single sided disc has capacities: Disc Type Sectors bytes GB GiB DVD-R SL 2,298,496 4,707,319,808 4.7 4.384 DVD+R SL 2,295,104 4,700,372,992 4.7 4.378 DVD-R DL 4,171,712 8,543,666,176 8.5 7.957 DVD+R DL 4,173,824 8,547,991,552 8.5 7.961 [edit] Capacity nomenclature The five basic types of DVD are referred to by their approximate capacity in gigabytes. DVD type Name Single sided, single layer DVD-5 Single sided, dual layer DVD-9 Double sided, single layer DVD-10 Double sided, dual layer on one side, single on other DVD-14[5] Double sided, dual layer on both sides DVD-18 [edit] Technology Internal mechanism of a DVD-ROM Drive DVD uses 650 nm wavelength laser diode light as opposed to 780 nm for CD. This permits a smaller spot on the media surface (1.32 µm for DVD versus 2.11 µm for CD). Writing speeds for DVD were 1×, that is 1350 kB/s (1318 KiB/s), in the first drives and media models. More recent models at 18× or 20× have 18 or 20 times that speed. Note that for CD drives, 1× means 153.6 kB/s (150 KiB/s), 9 times slower. DVD FAQ [edit] Speed Drive speed Data rate Write time for Single Layer DVD 1X 10.55 Mbit/s 1.32 MB/s 61 min. 2X 21.09 Mbit/s 2.64 MB/s 30 min. 4X 42.19 Mbit/s 5.27 MB/s 15 min. 8X 84.38 Mbit/s 10.55 MB/s 8 min. 16X 168.75 Mbit/s 21.09 MB/s 4 min. [edit] DVD recordable and rewritable Main article: DVD recordable HP initially developed recordable DVD media from the need to store data for back-up and transport. DVD recordables are now also used for consumer audio and video recording. Three formats were developed: DVD-R/RW (minus/dash), DVD+R/RW (plus), DVD-RAM. [edit] Dual layer recording Dual Layer recording allows DVD-R and DVD+R discs to store significantly more data, up to 8.5 Gigabytes per side, per disc, compared with 4.7 Gigabytes for single-layer discs. DVD-R DL was developed for the DVD Forum by Pioneer Corporation, DVD+R DL was developed for the DVD+RW Alliance by Philips and Mitsubishi Kagaku Media (MKM).[6] A Dual Layer disc differs from its usual DVD counterpart by employing a second physical layer within the disc itself. The drive with Dual Layer capability accesses the second layer by shining the laser through the first semi-transparent layer. The layer change mechanism in some DVD players can show a noticeable pause, as long as two seconds by some accounts. This caused more than a few viewers to worry that their dual layer discs were damaged or defective, with the end result that studios began listing a standard message explaining the dual layer pausing effect on all dual layer disc packaging. DVD recordable discs supporting this technology are backward compatible with some existing DVD players and DVD-ROM drives.[7] Many current DVD recorders support dual-layer technology, and the price is now comparable to that of single-layer drives, though the blank media remains more expensive. The recording speeds reached by dual-layer media are still well below those of single-layer media. [edit] DVD-Video Main article: DVD-Video DVD-Video is a standard for storing video content on DVD media. In the U.S., weekly DVD-Video rentals first out-numbered weekly VHS cassette rentals in June 2003, illustrating the rapid adoption rate of the technology in the marketplace.[8] Though many resolutions and formats are supported, most consumer DVD-Video discs use either 4:3 or anamorphic 16:9 aspect ratio MPEG-2 video, stored at a resolution of 720×480 (NTSC) or 720×576 (PAL) at 29.97 or 25 FPS. Audio is commonly stored using the Dolby Digital (AC-3) or Digital Theater System (DTS) formats, ranging from 16-bits/48kHz to 24-bits/96kHz format with monaural to 7.1 channel "Surround Sound" presentation, and/or MPEG-1 Layer 2. Although the specifications for video and audio requirements vary by global region and television system, many DVD players support all possible formats. DVD-Video also supports features like menus, selectable subtitles, multiple camera angles, and multiple audio tracks. [edit] DVD-Audio Main article: DVD-Audio DVD-Audio is a format for delivering high-fidelity audio content on a DVD. It offers many channel configuration options (from mono to 7.1 surround sound) at various sampling frequencies (up to 24-bits/192kHz versus CDDAs 16-bits/44.1kHz). Compared with the CD format, the much higher capacity DVD format enables the inclusion of considerably more music (with respect to total running time and quantity of songs) and/or far higher audio quality (reflected by higher linear sampling rates and higher vertical bit-rates, and/or additional channels for spatial sound reproduction). Despite DVD-Audio's superior technical specifications, there is debate as to whether the resulting audio enhancements are distinguishable in typical listening environments. DVD-Audio currently forms a niche market, probably due to the very sort of format war with rival standard SACD that DVD-Video avoided. [edit] Security Main article: Content Protection for Recordable Media DVD-Audio discs employ a robust copy prevention mechanism, called Content Protection for Prerecorded Media (CPPM) developed by the 4C group (IBM, Intel, Matsushita, and Toshiba). To date, CPPM has not been "broken" in the sense that DVD-Video's CSS has been broken, but ways to circumvent it have been developed.[9] By modifying commercial DVD(-Audio) playback software to write the decrypted and decoded audio streams to the hard disk, users can, essentially, extract content from DVD-Audio discs much in the same way they can from DVD-Video discs. [edit] Competitors and successors There are several possible successors to DVD being developed by different consortia. Sony/Panasonic's Blu-ray Disc (BD) and Toshiba's HD DVD began to gain traction in 2007, and next-generation technologies such as Maxell's Holographic Versatile Disc (HVD) and 3D optical data storage are being actively developed. On November 19, 2003, the DVD Forum decided by a vote of eight to six that HD DVD will be its official HD successor to DVD[citation needed]. In spite of this, both BD and HD DVD have already severely hampered the adoption of any successor to DVD through a lack of the very cooperation that fostered DVD's success. [edit] See also Blu-ray DiscCD and DVD packagingDIVX disposable DVDDualDiscDVD authoringDVD cover artDVD FormatsDVD region codeDVD TalkDVD TV GamesDVD-D disposable DVDDVD-RDVD-RAMDVD-RWDVD-VideoDVD+RDVD+RWEnhanced Versatile DiscFirmwareFlexplay disposable DVDHD DVDInkjet printable DVDList of DVD manufacturersMiniDVDMultiLevel RecordingMVINuonOptical discRiplockSpecial editionSuper Audio CDUser operation prohibition [edit] References ^ a b DVD Format Unification (press release). TOSHIBA (December 8, 1995). Retrieved on 2007-07-12.^ A Battle for Influence Over Insatiable Disks. New York Times (1995-01-11). Retrieved on 2007-04-09.^ DVD designers go with AC-3 Final specs for 'digital versatile disc'.... The Hollywood Reporter (1995-12-11). Retrieved on 2007-04-16.^ DVD FAQ. DVD Demystified (2006-09-12).^ DVD-14. AfterDawn Ltd.. Retrieved on 2007-02-06.^ Dual Layer Recording burnworld.com. Retrieved on 2007-07-06.^ Backwards Compatible burnworld.com. Retrieved on 2007-07-06.^ Bakalis, Anna (2003-06-20). It's unreel: DVD rentals overtake videocassettes. Washington Times.^ DVD-Audio's CPPM can be got around with a WinDVD patch. Retrieved on 2007-07-06. Bennett, Hugh (April 2004). Understanding Recordable & Rewritable DVD. Optical Storage Technology Association. Retrieved on 2006-12-17.Labarge, Ralph. DVD Authoring and Production. Gilroy, Calif.: CMP Books, 2001. ISBN 1-57820-082-2.Taylor, Jim. DVD Demystified, 2nd edition. New York: McGraw-Hill Professional, 2000. ISBN 0-07-135026-8. [edit] External links Wikibooks' Computer Science has more about this subject: All About Converting From Several Video Formats To DVD [edit] Official DVD ForumDVD+RW AllianceDVD Copy Control Association and the Content Scramble System (CSS) [edit] Quality guide Dual Layer Explained – Informational Guide to the Dual Layer Recording Process [edit] Knowledge Blank media quality guide & FAQUnderstanding Recordable & Rewritable DVD by Hugh BennettDVD Frequently Asked Questions (and Answers)DVDs: in the fast laneHistory of DVD technology from the Consumer Electronics AssociationHow Stuff Works - DVD [hide] v • d • e Industrial & home video media Magnetic tape Analog VERA (1952) • Quadruplex (1956) • Type A (1965) • Akai (1967) • U-matic (1969) • EIAJ-1 (1969) • Cartrivision (1972) • Philips VCR (1972) • V-Cord (1974) • VX (1974) • Betamax (1975) • IVC (1975) • Type B (1976) • Type C (1976) • VHS (1976) • VK (1977) • SVR (1979) • Video 2000 (1980) • CVC (1980) • VHS-C (1982) • M (1982) • Betacam (1982) • Video8 (1985) • MII (1986) • S-VHS (1987) • Hi8 (1989) • S-VHS-C (1987) • W-VHS (1994) Digital D1 (1986) • D2 (1988) • D3 (1991) • DCT (1992) • D5 (1994) • Digital Betacam (1993) • DV (1995) • Digital-S (D9) (1995) • DVCPRO (1995) • Betacam SX (1996) • DVCAM (1996) • HDCAM (1997) • DVCPRO50 (1998) • D-VHS (1998) • Digital8 (1999) • DVCPRO HD (2000) • D6 HDTV VTR (2000) • MicroMV (2001) • HDV (2003)• HDCAM SR (2003) Optical disc Analog Laserdisc (1978) • Laserfilm (1984) • CD Video (1986?) Digital VCD (1993) • MovieCD (1995?) • DVD/DVD-Video (1995) • MiniDVD • CVD (1998) • SVCD (1998) • FMD (2000) • EVD (2003) • HVD (2004) • FVD (2005) • UMD (2005) • VMD (2006) • HD DVD (2006) • Blu-ray Disc (BD) (2006) • DMD (2006?) • AVCHD (2006) • Tapestry Media (2007) • Total Hi Def (2008) • HVD (TBA) • PH-DVD (TBA) • SVOD (TBA) • Protein-coated disc (TBA) 3D disc (TBA) Grooved videodiscs Analog Baird Television Record aka Phonovision (1927) • TeD (1974) • Capacitance Electronic Disc aka CED (1981) • VHD (1983) Retrieved from "http://en.wikipedia.org/wiki/DVD" Categories: Optical disc authoring | All articles with unsourced statements | Articles with unsourced statements since February 2007 | Computer storage media | Audio storage | Video storage | DVD | 120 mm discs | Consumer electronics | 1996 introductions Views ArticleDiscussionEdit this pageHistory Personal tools Sign in / create account if (window.isMSIE55) fixalpha(); Navigation Main PageContentsFeatured contentCurrent eventsRandom article interaction About WikipediaCommunity portalRecent changesContact WikipediaDonate to WikipediaHelp Search Toolbox What links hereRelated changesUpload fileSpecial pagesPrintable versionPermanent linkCite this page Languages AfrikaansAlemannischالعربيةAsturianuবাংলাBosanskiБългарскиCatalàČeskyCymraegDanskDeutschEestiΕλληνικάEspañolEsperantoEuskaraفارسیFrançaisFryskGalego한국어HrvatskiIdoBahasa IndonesiaÍslenskaItalianoעבריתქართულიLietuviųMagyarBahasa MelayuNederlands日本語‪Norsk (bokmål)‬‪Norsk (nynorsk)‬PolskiPortuguêsRomânăРусскийShqipSimple EnglishSlovenčinaSlovenščinaСрпски / SrpskiSrpskohrvatski / СрпскохрватскиSuomiSvenskaTagalogไทยTiếng ViệtТоҷикӣTürkçeУкраїнська粵語中文 This page was last modified 15:44, 22 January 2008.All text is available under the terms of the GNU Free Documentation License. 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Homer at Home: Myth, Image, and the Ideology of Television
Peter Walsh
To begin, let me quote a passage from E. M. Forster’s first novel, Where Angels Fear to Tread, first
published in 1905. The scene is the Opera House of the imaginary Tuscan hill town of Monteriano.
“…soon the boxes began to fill… Families greeted each other across the auditorium. People
in the pit hailed their brothers and sons in the chorus and told them how well they were
singing. When Lucia appeared by the fountain there was a loud applause, and cries of
‘Welcome to Monteriano!’…
“The climax was reached in the mad scene. Lucia, clad in white, as befitted her malady,
suddenly gathered up her streaming hair and bowed her acknowledgement to the audience.
Then from the back of the stage--- she feigned not to see it--- there advanced a kind of
bamboo clotheshorse, stuck all over with bouquets. …they all knew the clotheshorse was a
piece of stage property, brought in to make the performance go year after year. Nonetheless
did it unloose the great deeps. With a scream of amazement and joy she embraced the
animal, pulled out one or two practicable blossoms, pressed them to her lips, and flung them
to her admirers. They flung them back, with loud melodious cries, and a little boy in one of
the stageboxes snatched up his sister’s carnations and offered them. ‘Che carino!’ exclaimed
the singer. She darted at the little boy and kissed him. Now the noise became tremendous.
‘Silence! Silence!’ shouted many old gentlemen behind. ‘Let the divine creature continue!’ But
the young men in the adjacent box were imploring Lucia to extend her civility to them. She
refused, with a humorous, expressive gesture. One of them hurled a bouquet at her. She
spurned it with her foot. Then, encouraged by the roars of the audience, she picked it up and
tossed it to them.”1
I have chosen to quote this passage, which we can assume is only slightly exaggerated from ones
Forster actually witnessed in Italy, because it illustrates the characteristics of a classic, communal
performance2. These characteristics include:
1. An audience and performers who are clearly defined, but are familiar and visible to each
other, appear in close proximity and are continuously interacting on several different levels.
2. An audience that is heterogeneous across class and age, but one with members who share
a common understanding of its own cultural norms.
3. Both individual audience members and the performers improvise and test certain public
roles. These roles are then either validated or challenged by the rest of the group.
4. The audience and performers share the collective task of creating a myth, understanding
implicitly both its significance and its provisional nature. This myth remains permeable and
always potentially subject to challenge and collapse. When successful evoked, however, this
myth is more compelling than the objective reality of the performance.
5. Both the myth and the performance that contains it only exist in a particular place and a
particular time. Although performances can be repeated and recorded in texts, each living
iteration will be different and will have different results and meanings.
“Myth is a type of speech…,” Roland Barthes has written, explaining that myth is essentially “…a system
of communication, … a message. This allows one to perceive that myth cannot possibly be an
object, a concept, or an idea; it is a mode of signification, a form.”3 It therefore follows that myth,
like language itself, can only be created and learned in public, by the sort of interaction a public
performance involves.
The original audiences for virtually all theatre that we now consider important were tiny and
provincial by modern mass-media standards. For most of human history, relatively small and
culturally homogeneous groups presented their collective myths in living performances created for
and by themselves. Whether the narrative appeared as Shakespeare at the Globe Theatre, a medieval
mystery play performed outside a great cathedral, or was presented by Jacob Adler on the stage of a
Second Avenue Yiddish theatre, the relationship between author, performers, and audience was
intimate and confined, limited in extent by the reach of the unamplified human voice. Small,
marginal, and even oppressed groups had their own identity myths and performances, which often
filtered into the larger society.
In historical models of performance, then, the validation of myth and performance only takes place
on an intimate level. The audience plays an indispensable role and its role is local. George Arliss, the
Anglo-American character actor, described one such audience from the South London theatre
where he began his career in the 1880s:
The patrons of the drama seldom showed resentment for anything done by an established
member of the company, but woe to the newcomer who took the place of some departed
favorite and who failed to come up to their expectations. They would listen with terribly
obvious patience for a long time and then some hardy regular Saturday-nighter would cry,
“We’ve heard enough.” This was the password that let loose the sinews of war, and a
vigorous fusillade of boos would almost surely follow4
The reality created by such performances was a collaborative construction jointly created by
audience and performers.5 Writing for a city with roughly the population of today’s Dayton, Ohio,
Shakespeare makes frequent allusions to this process of illusion and myth making in his plays. “Can
this cockpit hold the vasty fields of France?” he asks, rhetorically, in Henry V. “Or may we cram
within this wooden O the very casques that did affright the air at Agincourt?” The obvious answer is
“no,” at least not without the “imaginary forces” of the audience, which Shakespeare invites to
“piece out our imperfections with your thoughts.”6
British historian Norman Davies has noted Shakespeare’s success in creating, through his history
plays, the collective narrative of Great Britain: “The bard may have been careless about event-based
narrative, but he was very interested in other ways by which the past is remembered--- in myths,
legends, ideas, and popular misconceptions.”7 Davies quotes the distinguished Oxford medievalist
V. H. Galbraith “It is one of the penalties we pay… that our memory of [Shakespeare’s] history
plays, however imperfect, will outlast the most lucid account of the history books.”8
Let me turn to the nature of television.
Television is, so far as I know, the only medium to have its entire political, economic, and corporate
structure--- even its ownership--- planned out for it before it was invented. This was the structure
originally developed for radio. Commercial radio broadcasters, in fact, anticipated and prepared for
the development of television in the 1920s, and began experimental television broadcasting by the
end of the decade.
By the time television broadcasts became widespread in the late 1940s, the entire structure of radio--
- including the three major networks, a government regulatory structure which eliminated amateur
broadcasters, economic support provided by commercial advertising, many of the sponsors, and
much of the original programming--- had been transposed into the new medium, which quickly
replaced radio as the leading broadcast medium for news, variety shows, and dramatic
entertainment.9
The structure and technology of commercial television radically altered the nature of performance
and myth making. With television, the audience becomes invisible not only to the performers but
also--- and more critically--- to itself. This is a change even from cinema performance, in which
audience members can still see and hear each other, and then can gauge the group’s reaction to what
is presented.
Television also changes the audience for performance from a relatively small, local, and specific
group to a dramatically larger group, numbering in the millions, whose interests and tastes are no
longer tied to a specific location, class, or ethnic group. By reaching massive numbers at a relatively
low cost per individual, television essentially made all other forms of performance economically
obsolete. Whereas a theatre could survive, and even prosper, with a local audience numbered in
thousands, in commercial television, even audiences numbered in many millions are regularly
considered not economically viable. Thus television has the tendency to drive out the minority
voices, the performances created for a specific or even marginalized audience that once formed the
very core of theatre.
Like many technological media, television also tends to blur distinctions. The boundaries of myth
making, so carefully delineated by Shakespeare, are quite deliberately confused. Television mixes live
and recorded performance, fact and fiction, myth and reality in ways that were simply not possible
with theatre.
Television imposes a complicated and largely invisible system of censorship. Whereas Shakespeare
had only to avoid offending the Lord Chamberlain and a few politically important individuals,
television is subject to the censorship of commercial sponsors, producers, and executives as well as
politicians, government agencies and various citizen groups.
Sponsors direct television content not only to maximize profits, but also to avoid programming that
conflicted with the messages of commercials. One reason for the early demise of the live-television
dramas of the 1950s was their way of presenting everyday problems as complex and rooted in the
human condition. The story line of commercials, by contrast, always implies that a product quickly,
easily, and finally solves every problem. The result was often a conflict between content and
sponsorship that “made the commercial seem fraudulent.”10
The Cold War politics of the early television period--- and its McCarthyite pressure tactics on the
media--- also made television reluctant to explore anything that might be considered politically
controversial. As a result, television has always been highly self-censoring and has severely limited
the range of subjects it presents to the public.
Because of this self-censorship, television ideology proceeds primarily by omission--- editing out
material either because it is too controversial or because it does not appeal to an audience that is
broad enough or commercial enough. The formulae of television become a kind of compromise.
Controversies of private life are acceptable because these attract attention and suit the needs of the
sponsors. But in many other areas--- especially in the realm of serious politics and national myth
making--- much is grossed over or left out altogether.11
It is a common fallacy to assume that technology changes human beings in some
fundamental way. It does not. Although media and technology change culture in major ways,
the biology of the human mind and the basic way it analyzes the outside world remains the
same. Just as plant adjusts is growth as size depending on its surroundings, so the mind and
behavior adjust to fit these changes. Therefore to me the key to understanding media is
through understanding transformations--- the way one stage in human development changes
in response to changes in its environment.
Television almost immediately sensed that its very technology changed the relationship
between performance and audience. It tried to simulate, via every means at its disposal, the
spontaneity and close relationship to audience that live theatre had always provided. Hence
the insertion of “laugh tracks” into television comedies, hence the invention of the “studio
audience” --- an entity that is not a true audience but actually part of the performance.
Hence the introduction, most recently, of “reality television,” a type of performance as
consciously manipulated and false as anything else on television.
Because the essential message of commercial television must always be: “there is a product
to solve every problem,” there is always a split between the apparent and actual content.12
The apparent content is always a disguise or a distraction from the televisions true aim to sell
products. Thus television is, by its very nature, impermeable. It has become the projection of
images--- a series of changeless icons--- which cannot be modified or truly shared by an
audience. They can only be embraced or denied.
Projected globally, television-as-image is politically dangerous. Because television cannot fully
represent minority views---especially foreign minority views--- those who are left out of its
mythology are left without a complete identity. The outsiders’ only recourse is to break through the
television barrier by staging political events so catastrophic and visually spectacular that they can no
longer be ignored13. Thus we are increasingly assaulted, in real life, by pathological Hollywood
scenarios copied from television movies.
In his 1953 essay, “Television as Ideology,”: Adorno points to the “pseudo-realistic” as the core of
the television ideology. “The psychological process that is put on view is fraudulent--- in a word,
phony, for which there is utterly no equivalent in German.”14 Of course, all performance is “pseudorealistic.”
The difference that Adorno sensed nascent in early television was on a different order of
deception, one which steals myth-making from the heart if the community and replaces it with an
impenetrable image, created for the ends of a few. The results of this change will continue to
unfold.15
1 E.M. Forster, Where Angels Fear to Tread (New York: Gramercy Books, 1993), p. 67-68.
2 I am borrowing this term from David Thorburn (“Television as an Aesthetic Medium,” Critical Studies in Mass
Communication 4 [1987]: 161-173). Thorburn writes: “Homer’s oral epics, the plays of Sophocles, Aristophanes,
Plautus, even Shakespeare, continue to be experienced as narratives and as performances in our own day, but
we fool ourselves when we imagine or pretend that contemporary versions of such texts very closely resemble
their original, communal enactments.”
3 Roland Barthes, Mythologies, Annette Lavers, trans. (New York: Hill and Wang, 1975), p. 109.
4 George Arliss, Up the Years from Bloomsbury: An Autobiography (Boston: Little, Brown, and Company, 1927), p.
51.
5 In his famous play within a play, Shakespeare describes, in satirical terms, this give and take between performers and
audience in creating a metaphor for reality:
Moon: This lanthorn doth the horned moon present---
Demetrius: He should have worn the horns on his head.
Theseus: He is no crescent, and his horns are invisible within the circumference.
Moon: This lanthorn doth the horned moon present. Myself the man i’ th’ moon do seem to be.
Theseus: This is the greatest error of all the rest. The man should be put into the lanthorn. How else is
it the man i’ th’ moon?(A Midsummer’s Night Dream, V, I).
6 Henry V, prologue.
7 Norman Davies, The Isles: A History (Oxford: Oxford University Press, 1999), p. 509.
8 Quoted in Ibid., p. 506.
9 For details on the early history and organization of television, see Erik Barnouw, Tube of Plenty: The Evolution of
American Televison, 2nd edition, revised (Oxford: Oxford University Press, 1990).
10 Ibid., p. 163.
11 It has been noted, for example, that as the Al-Qaeda terrorists made final preparations for their September 11 attack,
American television was obsessed with the private life of a minor American politician.
12 Although paid and public television were supposed to eliminate this split, they have not, in fact, altered the
basic premise of television, which has changed the economic covenant between performance and audience.
The covenant of commercial theatre was “pay us a fee, we will give you a wonderful experience, and then we
will go away.” The covenant of all kinds of television is “pay us forever.”
13 The terrorist attacks of September 11, 2001, in New York City were the culmination, and to some extent the
perfection, of a long history of attempts to penetrate and subvert television to promote the cause of
“outsiders.” These terrorists grossly underestimate, however, the ability of the medium to absorb such images
into its own mythology, as almost immediately occurred with the September 11 events.
14 Adorno, op. cit., p. 65.
15 Beyond the scope of this paper are the implications of the World Wide Web, which one again give voice to
many minority and marginalized voices. As television and Internet-type technologies merge, the basic effects of
television may change or even reverse.

Television Violence: A Review of the Effects on Children of Different Ages Summary of Recommendations Report of the Department of
Canadian Heritage, Feb. 1995
Wendy L. Josephson, Ph.D.
Republished with permission the
Minister of Public Works and Government Services Canada Full document includes:

Executive Summary

Introduction

Infants (Children up to 18 Months):

Toddlers (Children 18 Months to 3 Years Old):

Early Childhood or Preschool Age (Children Ages 3 to 5):

Middle Childhood or Elementary School Age (Children Ages 6 to 11):

Adolescence (Children Ages 12 to 17):

Conclusion

Appendix I: Effects of Television Violence on Especially Vulnerable Groups

Appendix II: Responses to Common Criticisms of Research on the Relationship between Television Violence and Aggression

Appendix III: Research on the Effects of Violent Video Games

References
Children of different ages watch and understand television in different ways, depending on the length of their attention spans, the ways in which they process information, the amount of mental effort they invest, and their own life experiences. These variables must all be examined to gain an understanding of how television violence affects them.

Infants (children up to 18 months old) can pay attention to an operating television set for short periods of time, but the attention demands a great effort and infants are usually more interested in their own activities. Even when they do pay attention to the television, infants likely miss most of what adults consider to be program content. They experience it primarily as fragmented displays of light and sound, which they are only intermittently able to group into meaningful combinations such as recognizable human or animal characters.

No research has focused specifically on how violent content affects infants, but there is some evidence that infants can imitate behaviour from television when that behaviour is presented in a simple, uncluttered and instructional manner.

Children do not become full-fledged "viewers" until around the age of two-and-a-half. As toddlers, they begin to pay more attention to the television set when it is on, and they develop a limited ability to extract meaning from television content. They are likely to imitate what they see and hear on television.

The viewing patterns children establish as toddlers will influence their viewing habits throughout their lives. Since toddlers have a strong preference for cartoons and other programs that have characters who move fast, there is considerable likelihood that they will be exposed to large amounts of violence.

At the preschool age (three to five years old), children begin watching television with an "exploration" approach. They actively search for meaning in the content, but are still especially attracted to vivid production features, such as rapid character movement, rapid changes of scene, and intense or unexpected sights and sounds.

Because television violence is accompanied by vivid production features, preschoolers are predisposed to seek out and pay attention to violence—particularly cartoon violence. It is not the violence itself that makes the cartoons attractive to preschoolers, but the accompanying vivid production features. With this preference for cartoons, preschoolers are being exposed to a large number of violent acts in their viewing day. Moreover, they are unlikely to be able to put the violence in context, since they are likely to miss any subtlety conveyed mitigating information concerning motivation and consequences. Preschoolers behave more aggressively than usual in their play after watching any high-action exciting television content, but especially after watching violent television.

Elementary school age (ages six to eleven) is considered a critical period for understanding the effects of television on aggression. At this stage, children develop the attention span and cognitive ability to follow continuous plots, to make inferences about implicit content, and to recognize motivations and consequences to characters' actions. However, they are also investing increasingly less mental effort overall in their viewing, and it is mental effort that determines whether children will process television information deeply or merely react to it in an unfocused, superficial way.

By age eight, children are more likely to be sensitive to important moderating influences of television content, and will not become more aggressive themselves if the violence they see is portrayed as evil, as causing human suffering, or as resulting in punishment or disapproval. However, they are especially likely to show increased aggression from watching violent television if they believe the violence reflects real life, if they identify with a violent hero (as boys often do), or if they engage in aggressive fantasies.

At ages 6 to 11, elementary school children still watch cartoons but also begin watching more adult or family-oriented programming than they did when they were younger. They also develop a surprising taste for horror movies, perhaps deliberately scaring themselves in an attempt to overcome their own fears. However, to the extent that they are desensitizing themselves to fear and violence, they are also very likely becoming more tolerant of violence in the real world.

During adolescence (age 12 to 17), the middle school to high school years, children become capable of high levels of abstract thought and reasoning, although they rarely use these abilities when watching television, continuing to invest little mental effort. They watch less television than they did when they were younger, and watch less with their families. Their interests at this age tend to revolve around independence, sex and romance, and they develop a preference for music videos, horror movies, and (boys particularly) pornographic videos, which deal with these topics, although usually in negative ways.

Adolescents in middle school and high school are much more likely than younger children to doubt the reality of television content and much less likely to identify with television characters. The small percentage of those who continue to believe in the reality of television and to identify with its violent heroes are the ones likely to be more aggressive, especially if they continue to fantasize about aggressive-heroic themes.

Their superior abstract reasoning abilities and their tendency at this age to challenge conventional authority make adolescents particularly susceptible to imitating some kinds of television violence, crime and portrayals of suicide. However, these imitative acts affect only a small percentage of adolescents.

In a world in which violent television is pervasive and children are susceptible to its effects, parents are the best mediators of their children's viewing.

There are a number of ways parents can limit their children's exposure to violence. Restricting the amount and types of programs children watch is probably the most effective and common means of mediation for children of all ages. However, there are also strategies that are specifically appropriate for children at different ages.

Under normal conditions, parents probably do not need to worry too much about their infants being negatively influenced by television, although they might want to limit their exposure to violence or other portrayals it might be dangerous for an infant to imitate.

Limiting exposure to this kind of TV content is especially wise with toddlers, who are even more prone to imitating what they see on television. Another highly influential action parents can take for toddlers is to examine and regulate their own viewing behaviour, since toddlers are highly influenced by their parents' viewing habits.

Parental mediation to reduce a preschooler's aggression (as well as fears from what they see on television) can include viewing with the child, commenting on content, providing distraction or comfort if the child is frightened, and encouraging or discouraging behaviour they see preschoolers imitating from television.

While restricting viewing is an effective form of parental mediation for younger elementary school aged children, for older children it is more useful for parents to discuss, explain, and challenge television. By doing so, parents can help their children to interpret television material and overcome the effect televised violence has on their attitudes and behaviour. Another positive effect of these strategies is that children invest more mental effort in their watching, becoming more critical and analytical viewers.

Encouraging adolescents to express their opinions and to analyze and question television content is a parental strategy that has been found to reduce adolescents' fears and aggressiveness, as well as to improve their critical approach to the medium.

There is an unfortunate lack of non-violent educational and entertaining programming specifically geared to children. It would not be a difficult challenge to come up with non-violent programming, since it is not the violence itself that attracts viewers. The television industry would do well to create programming specifically aimed at child audiences, taking into account the various approaches to watching television and the interests of each age group.

Although toddlers do not understand a great deal of program content, creating educational programming using such features as animation, children's or women's voices on the sound track, and simplified movements and camera work will likely win them as loyal viewers. A habit of watching educational programs (as opposed to cartoons) will reduce their exposure to violent content and make it more likely that they will watch and benefit from educational television later on, as preschoolers.

For preschoolers, effective programming would include the use of vivid production features and "child-directed speech" (simple sentences spoken slowly, referring to objects that are actually being shown on the screen, and with repetition). These features will improve their attention and understanding and can be used to highlight important features of program content, such as critical plot events.

The elementary school-aged audience has been called the "almost forgotten group" when it comes to targeted programming. Such programming could easily avoid violence, since children at this age are still more attracted to variability and tempo than to violence. Although boys, particularly, seek out male heroes who tend to be violent, it is actually the hero's power (not the violence) that is the attraction. Strong, yet positive, counterstereotypical television characters could be created to fit the bill, since these have proven to equally attract their interest, as effectively as violent heroes.

Programming for adolescents should avoid promoting rape myths and portraying violent behaviour that promises fun, "kicks," or instant notoriety. It might lessen the number of horror and pornographic videos that adolescents watch if television programming were provided that addresses their particular needs and interests.

It is certainly true that television violence does not account for all the causes of children's aggression, and it is also true that some children are a great deal more likely to be affected by television violence than others, and that it is these children who are likely to be potentially more aggressive anyway. But the effect of television violence leads these "at-risk" children to be even more aggressive than they would otherwise be. And although the group especially at risk might be a minority of viewers, they are likely to be the majority of aggressors. This fact makes them, and the violent content of television, worthy of our attention.

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Television

Television From Wikipedia, the free encyclopedia Jump to: navigation, search This article does not cite any references or sources. (December 2007)
Please help improve this article by adding citations to reliable sources. Unverifiable material may be challenged and removed. This article may require cleanup to meet Wikipedia's quality standards.
Please improve this article if you can. (December 2007) "TV" redirects here. For other uses, see TV (disambiguation). For the band, see Television (band). Braun HF 1, Germany, 1959 Clivia II FER858A (VEB Rafena, Radeberg, Germany), 1956 Television (often abbreviated to TV) is a widely used telecommunication system for broadcasting and receiving moving pictures and sound over a distance. The term may also be used to refer specifically to a television set, programming or television transmission. The word is derived from mixed Latin and Greek roots, meaning "far sight": Greek tele (τῆλε), far, and Latin vision, sight (from video, vis- to see, or to view in the first person). Since it first became commercially available from the late 1930s, the television set has become a common household communications device in homes and institutions, particularly in the First World, as a source of entertainment and news. Since the 1970s, video recordings on VCR tapes and later, digital playback systems such as DVDs, have enabled the television to be used to view recorded movies and other programs. A television system may be made up of multiple components, so a screen which lacks an internal tuner to receive the broadcast signals is called a monitor rather than a television. A television may be built to receive different broadcast or video formats, such as high-definition television, commonly referred to as HDTV. HDTV costs more than normal TV but is becoming more available. Contents [hide] 1 History2 Technology3 Geographical usage4 Content 4.1 Programming4.2 Funding4.3 Television genres 5 Social aspects6 Environmental aspects7 References8 Further reading9 External links // [edit] History Main article: History of television [edit] Technology Main article: Technology of television [edit] Geographical usage Timeline of the introduction of television in countries Main article: Geographical usage of television [edit] Content [edit] Programming See also: Category:Television genres Getting TV programming shown to the public can happen in many different ways. After production the next step is to market and deliver the product to whatever markets are open to using it. This typically happens on two levels: Original Run or First Run – a producer creates a program of one or multiple episodes and shows it on a station or network which has either paid for the production itself or to which a license has been granted by the producers to do the same.Syndication – this is the terminology rather broadly used to describe secondary programming usages (beyond original run). It includes secondary runs in the country of first issue, but also international usage which may or may not be managed by the originating producer. In many cases other companies, TV stations or individuals are engaged to do the syndication work, in other words to sell the product into the markets they are allowed to sell into by contract from the copyright holders, in most cases the producers. In most countries, the first wave occurs primarily on free-to-air (FTA) television, while the second wave happens on subscription TV and in other countries. In the U.S., however, the first wave occurs on the FTA networks and subscription services, and the second wave travels via all means of distribution. First run programming is increasing on subscription services outside the U.S., but few domestically produced programs are syndicated on domestic FTA elsewhere. This practice is increasing however, generally on digital-only FTA channels, or with subscriber-only first run material appearing on FTA. Unlike the U.S., repeat FTA screenings of a FTA network program almost only occur on that network. Also, Affiliates rarely buy or produce non-network programming that is not centred around local events. [edit] Funding The examples and perspective in this section may not represent a worldwide view of the subject.
Please improve this article or discuss the issue on the talk page. Advertising United States Since inception in the U.S. in 1940, TV commercials have become one of the most effective, persuasive, and popular method of selling products of many sorts, especially consumer goods. U.S. advertising rates are determined primarily by Nielsen Ratings. The time of the day and popularity of the channel determine how much a television commercial can cost. For example, the highly popular American Idol can cost approximately $750,000 for a thirty second block of commercial time; while the same amount of time for the World Cup and the Super Bowl can cost several million dollars. In recent years, the paid program or infomercial has become common, usually in lengths of 30 minutes or one hour. Some drug companies have even created "news" items for broadcast, paying program directors to use them.[citation needed] [1] Some TV programs also weave advertisements into their shows, a practice begun in film and known as product placement. For example, a character could be drinking a certain kind of soda, going to a particular chain restaurant, or driving a certain make of car. (This is sometimes very subtle, where shows have vehicles provided by manufacturers for low cost, rather than wrangling them.) Sometimes a specific brand or trade mark, or music from a certain artist or group, is used. (This excludes guest appearances by artists, who perform on the show.) United Kingdom The TV regulator oversees the TV advertising in the United Kingdom. Its restrictions have applied since the early days of commercially funded TV in the UK. Despite this, the demand from advertisers ensured that ownership of a commercial broadcasting licence was, at one time, likened by the TV mogul, Lew Grade, as a being a "licence to print money". The restrictions mean that the big three national commercial TV channels, ITV, Channel 4, and Five can show an average of only seven minutes of advertising per hour (eight minutes in the peak period). Other broadcasters must average no more than nine minutes (twelve in the peak). This means that many imported TV shows from the US have un-natural breaks where the UK company has edited out the breaks intended for US advertising. Advertisements must not be inserted in the course of any broadcast of a news or current affairs program of less than half an hour scheduled duration, or in a documentary of less than half an hour scheduled duration, or in a program for children of less than half an hour scheduled duration. Nor may advertisements be carried in a program designed and broadcast for reception in schools or in any religious service or other devotional program, or during a formal Royal ceremony or occasion. There also must be clear demarcations in time between the programs and the advertisements. The BBC, being strictly non-commercial is not allowed to show advertisements on television, the majority of its budget comes from TV licencing (see below). Taxation or TV License Television services in some countries may be funded by a television licence, a form of taxation which means advertising plays a lesser role or no role at all. For example, in the United Kingdom, and in many European countries, some channels may carry no advertising at all and some very little. The British Broadcasting Corporation (BBC) carries no advertising and is funded by an annual licence paid by all households owning a television. This licence fee is set by government, but the BBC is not answerable to or controlled by government and is therefore genuinely independent. The fee also funds radio channels, transmitters and the BBC.co.uk online service. Advertising has been introduced to the internationally-facing BBC.com website in a small way to fund broadband content delivered outside of the United Kingdom. Subscription Some TV channels are partly funded from subscriptions and therefore the signals are encrypted before broadcast to ensure that only paying subscribers have access to the decryption codes. Some subscription services are also funded by advertising. [edit] Television genres Television genres include a broad range of programming types that entertain, inform, and educate viewers. The most expensive entertainment genres to produce are usually drama and dramatic miniseries. However, other genres, such as historical Western genres, may also have high production costs. Popular entertainment genres include action-oriented shows such as police, crime, detective dramas, horror or thriller shows. As well, there are also other variants of the drama genre, such as medical dramas and daytime soap operas. Sci-fi (Science fiction) shows can fall into either the drama category or the action category, depending on whether they emphasize philosophical questions or high adventure. Comedy is a popular genre which includes sitcoms (Situation Comedy) and animated shows for the adult demographic such as Family Guy. The least expensive forms of entertainment programming are game shows, talk shows, variety shows, and reality TV. Game shows show contestants answering questions and solving puzzles to win prizes. Talk shows feature interviews with film, television and music celebrities and public figures. Variety shows feature a range of musical performers and other entertainers such as comedians and magicians introduced by a host or Master of Ceremonies. There is some crossover between some talk shows and variety shows, because leading talk shows often feature performances by bands, singers, comedians, and other performers in between the interview segments. Reality TV shows show "regular" people (i.e., not actors) who are facing unusual challenges or experiences, ranging from arrest by police officers (COPS) to weight loss (The Biggest Loser). A variant version of reality shows depicts celebrities doing mundane activities such as going about their everyday life (The Osbournes) or doing manual labour jobs (Simple Life). One of the television genres, the children's and youth genre is defined by the audience, rather than by the content of the programming. Children's programming includes animated programs aimed at the child demographic, documentaries for children, and music/variety shows targeted at kids. There is overlap between the children's/youth genre and other genres, such as the educational genre. [edit] Social aspects Main article: Social aspects of television Television has played a pivotal role in the socialization of the 20th and 21st centuries. There are many social aspects of television that can be addressed, including: Positive effectsNegative effectsGender and televisionPolitics and televisionSocializing childrenTechnology trendsSuitability for audienceAlleged dangersPropaganda deliveryEducational advantages [edit] Environmental aspects With high lead content in CRTs, and the rapid diffusion of new, flat-panel display technologies, some of which (LCDs) use lamps containing mercury, there is growing concern about electronic waste from discarded televisions. Related occupational health concerns exist, as well, for disassemblers removing copper wiring and other materials from CRTs. Further environmental concerns related to television design and use relate to the devices' increasing electrical energy requirements.[2] Some speculate that television is responsible for a "dumbing down" of modern peoples. Several articles have been written by numerous individuals, and watchgroups. One theory is that the passive state of the brain leads to a form of mental atrophy. While watching television the higher functions of the brain slow down and in some cases cease. There are ongoing studies to determine the risk of this passive activity.[3] [edit] References ^ Jon Stewart of "The Daily Show" was mock-outraged at this, saying, "That's what we do!", and calling it a new form of television, "infoganda".^ The Rise of the Machines: A Review of Energy Using Products in the Home from the 1970s to Today (PDF). Energy Saving Trust (July 3, 2006). Retrieved on 2007-08-31.^ Watching Television: Experiments on the Viewing Process.. [edit] Further reading Find more about Television on Wikipedia's sister projects: Dictionary definitions Textbooks Quotations Source texts Images and media News stories Learning resources Albert Abramson, The History of Television, 1942 to 2000, Jefferson, NC, and London, McFarland, 2003, ISBN 0786412208.Pierre Bourdieu, On Television, The New Press, 2001.Tim Brooks and Earle March, The Complete Guide to Prime Time Network and Cable TV Shows, 8th ed., Ballantine, 2002.Jacques Derrida and Bernard Stiegler, Echographies of Television, Polity Press, 2002.David E. Fisher and Marshall J. Fisher, Tube: the Invention of Television, Counterpoint, Washington, DC, 1996, ISBN 1887178171.Steven Johnson, Everything Bad is Good for You: How Today's Popular Culture Is Actually Making Us Smarter, New York, Riverhead (Penguin), 2005, 2006, ISBN 1594481946.Jerry Mander, Four Arguments for the Elimination of Television, Perennial, 1978.Jerry Mander, In the Absence of the Sacred, Sierra Club Books, 1992, ISBN 0871565099.Neil Postman, Amusing Ourselves to Death: Public Discourse in the Age of Show Business, New York, Penguin US, 1985, ISBN 0670804541.Evan I. Schwartz, The Last Lone Inventor: A Tale of Genius, Deceit, and the Birth of Television, New York, Harper Paperbacks, 2003, ISBN 0060935596.Beretta E. Smith-Shomade, Shaded Lives: African-American Women and Television, Rutgers University Press, 2002.Alan Taylor, We, the Media: Pedagogic Intrusions into US Mainstream Film and Television News Broadcasting Rhetoric, Peter Lang, 2005, ISBN 3631518528.

Microphone

Microphone From Wikipedia, the free encyclopedia Jump to: navigation, search "Microphones" redirects here. For the Indie band, see The Microphones. A microphone, sometimes referred to as a mike or mic (both pronounced /ˈmaɪk/), is an acoustic to electric transducer or sensor that converts sound into an electrical signal. A Neumann U87 capacitor microphone Microphones are used in many applications such as telephones, tape recorders, hearing aids, motion picture production, live and recorded audio engineering, in radio and television broadcasting and in computers for recording voice, VoIP, and for non-acoustic purposes such as ultrasonic checking. Contents [hide] 1 History2 Principle of operation3 Microphone varieties 3.1 Condenser, capacitor or electrostatic microphones 3.1.1 Technology 3.1.1.1 DC-biased microphone operating principle3.1.1.2 RF condenser microphone operating principle 3.1.2 Usage3.1.3 Electret condenser microphones 3.2 Dynamic microphones 3.2.1 Moving coil microphones 3.2.1.1 Technology 3.3 Ribbon microphones3.4 Carbon microphones3.5 Piezoelectric microphones 3.5.1 Technology3.5.2 Usage 3.6 Laser microphones 3.6.1 Usage 3.7 Liquid microphones 3.7.1 Technology3.7.2 Usage 3.8 MEMS microphones3.9 Speakers as microphones 4 Capsule design and directivity5 Microphone polar patterns 5.1 Omnidirectional5.2 Unidirectional5.3 Cardioids5.4 Bi-directional5.5 Shotgun 6 Application-specific microphone designs7 Connectivity 7.1 Connectors7.2 Impedance matching7.3 Digital microphone interface 8 Measurements and specifications9 Measurement microphones 9.1 Microphone calibration techniques 9.1.1 Pistonphone apparatus9.1.2 Reciprocal method 10 Microphone array and array microphones11 Microphone windscreens12 See also13 References14 External links // [edit] History Several early inventors built primitive microphones (then called transmitters) prior to Alexander Bell, but the first commercially practical microphone was the carbon microphone conceived in October 1876 by Thomas Edison. Many early developments in microphone design took place at Bell Laboratories. [edit] Principle of operation Edmund Lowe away from the mic A microphone is a device made to capture waves in air, water (hydrophone) or hard material and translate them into an electrical signal. The most common method is via a thin membrane producing some proportional electrical signal. Most microphones in use today for audio use electromagnetic generation (dynamic microphones), capacitance change (condenser microphones) or piezoelectric generation to produce the signal from mechanical vibration. [edit] Microphone varieties [edit] Condenser, capacitor or electrostatic microphones Inside the Oktava 319 condenser microphone. [edit] Technology In a condenser microphone, also known as a capacitor microphone, the diaphragm acts as one plate of a capacitor, and the vibrations produce changes in the distance between the plates. There are two methods of extracting an audio output from the transducer thus formed. They are known as DC biased and RF (or HF) condenser microphones. [edit] DC-biased microphone operating principle The plates are biased with a fixed charge (Q). The voltage maintained across the capacitor plates changes with the vibrations in the air, according to the capacitance equation: where Q = charge in coulombs, C = capacitance in farads and V = potential difference in volts. The capacitance of the plates is inversely proportional to the distance between them for a parallel-plate capacitor. (See capacitance for details.) A nearly constant charge is maintained on the capacitor. As the capacitance changes, the charge across the capacitor does change very slightly, but at audible frequencies it is sensibly constant. The capacitance of the capsule and the value of the bias resistor form a filter which is highpass for the audio signal, and lowpass for the bias voltage. Note that the time constant of a RC circuit equals the product of the resistance and capacitance. Within the time-frame of the capacitance change (on the order of 100 μs), the charge thus appears practically constant and the voltage across the capacitor adjusts itself instantaneously to reflect the change in capacitance. The voltage across the capacitor varies above and below the bias voltage. The voltage difference between the bias and the capacitor is seen across the series resistor. The voltage across the resistor is amplified for performance or recording. An Oktava condenser microphone. [edit] RF condenser microphone operating principle In a DC-biased condenser microphone, a high capsule polarisation voltage is necessary. In contrast, RF condenser microphones use a comparatively low RF voltage, generated by a low-noise oscillator. The oscillator is frequency modulated by the capacitance changes produced by the sound waves moving the capsule diaphragm. Demodulation yields a low-noise audio frequency signal with a very low source impedance. This technique achieves better low frequency response - in fact it will theoretically operate down to DC. The RF biasing process results in a lower electrical impedance capsule, a useful byproduct of which is that RF condenser microphones can be operated in damp weather conditions which would effectively short out a DC biased microphone. The Sennheiser "MKH" series of microphones use the RF biased technique. [edit] Usage Condenser microphones span the range from cheap throw-aways to high-fidelity quality instruments. They generally produce a high-quality audio signal and are now the popular choice in laboratory and studio recording applications. They require a power source, provided either from microphone inputs as phantom power or from a small battery. Power is necessary for establishing the capacitor plate voltage, and is also needed for internal amplification of the signal to a useful output level. Condenser microphones are also available with two diaphragms, the signals from which can be electrically connected such as to provide a range of polar patterns (see below), such as cardioid, omnidirectional and figure-eight. It is also possible to vary the pattern smoothly with some microphones, for example the Røde NT2000. [edit] Electret condenser microphones Main article: Electret microphone First patent on foil electret microphone by G. M. Sessler et al. (pages 1 to 3) An electret microphone is a relatively new type of capacitor microphone invented at Bell laboratories in 1962 by Gerhard Sessler and Jim West[1]. An electret is a ferroelectric material that has been permanently electrically charged or polarized. The name comes from electrostatic and magnet; a static charge is embedded in an electret by alignment of the static charges in the material, much the way a magnet is made by aligning the magnetic domains in a piece of iron. They are used in many applications, from high-quality recording and lavalier use to built-in microphones in small sound recording devices and telephones. Though electret microphones were once low-cost and considered low quality, the best ones can now rival capacitor microphones in every respect and can even offer the long-term stability and ultra-flat response needed for a measuring microphone. Unlike other capacitor microphones, they require no polarizing voltage, but normally contain an integrated preamplifier which does require power (often incorrectly called polarizing power or bias). This preamp is frequently phantom powered in sound reinforcement and studio applications. While few electret microphones rival the best DC-polarized units in terms of noise level, this is not due to any inherent limitation of the electret. Rather, mass production techniques needed to produce electrets cheaply don't lend themselves to the precision needed to produce the highest quality microphones. [edit] Dynamic microphones Dynamic microphones work via electromagnetic induction. They are robust, relatively inexpensive and resistant to moisture, and for this reason they are widely used on-stage by singers. There are two basic types: the moving coil microphone and the ribbon microphone. [edit] Moving coil microphones The Shure SM57 and Beta 57A dynamic microphones [edit] Technology The dynamic principle is exactly the same as in a loudspeaker, only reversed. A small movable induction coil, positioned in the magnetic field of a permanent magnet, is attached to the diaphragm. When sound enters through the windscreen of the microphone, the sound wave moves the diaphragm. When the diaphragm vibrates, the coil moves in the magnetic field, producing a varying current in the coil through electromagnetic induction. A single dynamic membrane will not respond linearly to all audio frequencies. Some microphones for this reason utilize multiple membranes for the different parts of the audio spectrum and then combine the resulting signals. Combining the multiple signals correctly is difficult and designs that do this are rare and tend to be expensive. There are on the other hand several designs that are more specifically aimed towards isolated parts of the audio spectrum. AKG D112 is for example designed for bass content rather than treble. In audio engineering several kinds of microphones are often used at the same time to get the best result. [edit] Ribbon microphones Main article: Ribbon microphone In ribbon microphones a thin, usually corrugated metal ribbon is suspended in a magnetic field. The ribbon is electrically connected to the microphone's output, and its vibration within the magnetic field generates the electrical signal. Ribbon microphones are similar to moving coil microphones in the sense that both produce sound by means of magnetic induction. Basic ribbon microphones detect sound in a bidirectional (also called figure-eight) pattern because the ribbon, which is open to sound both front and back, responds to the pressure gradient rather than the sound pressure. Though the symmetrical front and rear pickup can be a nuisance in normal stereo recording, the high side rejection can be used to advantage by positioning a ribbon microphone horizontally, for example above cymbals, so that the rear lobe picks up only sound from the cymbals. Crossed figure 8, or Blumlein stereo recording is gaining in popularity, and the figure 8 response of a ribbon microphone is ideal for that application. Other directional patterns are produced by enclosing one side of the ribbon in an acoustic trap or baffle, allowing sound to reach only one side. Older ribbon microphones, some of [edit] Carbon microphones Main article: Carbon microphone A carbon microphone, formerly used in telephone handsets, is a capsule containing carbon granules pressed between two metal plates. A voltage is applied across the metal plates, causing a small current to flow through the carbon. One of the plates, the diaphragm, vibrates in sympathy with incident sound waves, applying a varying pressure to the carbon. The changing pressure deforms the granules, causing the contact area between each pair of adjacent granules to change, and this causes the electrical resistance of the mass of granules to change. The changes in resistance cause a corresponding change in the voltage across the two plates, and hence in the current flowing through the microphone, producing the electrical signal. Carbon microphones were once commonly used in telephones; they have extremely low-quality sound reproduction and a very limited frequency response range, but are very robust devices. Unlike other microphone types, the carbon microphone can also be used as a type of amplifier, using a small amount of sound energy to produce a larger amount of electrical energy. Carbon microphones found use as early telephone repeaters, making long distance phone calls possible in the era before vacuum tubes. These repeaters worked by mechanically coupling a magnetic telephone receiver to a carbon microphone: the faint signal from the receiver was transferred to the microphone, with a resulting stronger electrical signal to send down the line. (One illustration of this amplifier effect was the oscillation caused by feedback, resulting in an audible squeal from the old "candlestick" telephone if its earphone was placed near the carbon microphone.) [edit] Piezoelectric microphones [edit] Technology A crystal microphone uses the phenomenon of piezoelectricity—the ability of some materials to produce a voltage when subjected to pressure—to convert vibrations into an electrical signal. An example of this is Rochelle salt (potassium sodium tartrate), which is a piezoelectric crystal that works as a transducer, both as a microphone and as a slimline loudspeaker component. [edit] Usage Crystal microphones used to be commonly supplied with vacuum tube (valve) equipment, such as domestic tape recorders. Their high output impedance matched the high input impedance (typically about 10 megohms) of the vacuum tube input stage well. They were difficult to match to early transistor equipment, and were quickly supplanted by dynamic microphones for a time, and later small electret condenser devices. The high impedance of the crystal microphone made it very susceptible to handling noise, both from the microphone itself and from the connecting cable. Piezo transducers are often used as contact microphones to amplify sound from acoustic musical instruments, to sense drum hits for triggering electronic samples and to record sound in challenging environments, such as underwater under high pressure. Saddle-mounted pickups on acoustic guitars are generally piezos that contact the strings passing over the saddle. This type of microphone is different from magnetic coil pickups commonly visible on typical electric guitars, which use magnetic induction rather than mechanical coupling to pick up vibration. [edit] Laser microphones Main article: Laser microphone [edit] Usage Laser microphones are very rare and expensive, and are most commonly portrayed in movies as spying devices. [edit] Liquid microphones Main article: Water microphone [edit] Technology Early microphones did not produce intelligible speech, until Alexander Graham Bell made improvements including a variable resistance microphone/transmitter. Bell’s liquid transmitter consisted of a metal cup filled with water with a small amount of sulfuric acid added. A sound wave caused the diaphragm to move, forcing a needle to move up and down in the water. The electrical resistance between the wire and the cup was then inversely proportional to the size of the water meniscus around the submerged needle. Elisha Gray filed a caveat for a version using a brass rod instead of the needle. Other minor variations and improvements were made to the liquid microphone by Majoranna, Chambers, Vanni, Sykes, and Elisha Gray, and one version was even patented by Reginald Fessenden in 1903. [edit] Usage These were the first working microphones, but they were not practical for commercial application and are utterly obsolete now. It was with a liquid microphone that the famous first phone conversation between Bell and Watson took place. Other inventors, especially Thomas Edison, soon devised superior microphones. [edit] MEMS microphones The MEMS microphone is also called a microphone chip or silicon microphone. The pressure-sensitive diaphragm is etched directly on a silicon chip by MEMS (MicroElectrical-Mechanical Systems) techniques[citation needed], and is usually accompanied with integrated preamplifier. Most MEMS microphones are modern embodiments of the standard condenser microphone. Often MEMS mics have a built in ADC on the same CMOS chip making the chip a digital microphone and easily integrated into modern digital products. Major manufacturers using MEMS manufacturing for silicon microphones are Akustica (AKU200x), Infineon (SMM310 product), Knowles Electronics and Sonion MEMS. [edit] Speakers as microphones A loudspeaker, a transducer that turns an electrical signal into sound waves, is the functional opposite of a microphone. Since a conventional speaker is constructed much like a dynamic microphone (with a diaphragm, coil and magnet), speakers can actually work "in reverse" as microphones. The result, though, is a microphone with poor quality, limited frequency response (particularly at the high end), and poor sensitivity. In practical use, speakers are sometimes used as microphones in such applications as intercoms or walkie-talkies, where high quality and sensitivity are not needed. However, there is at least one other practical application of this principle: using a medium-size woofer placed closely in front of a "kick" (bass drum) in a drum set to act as a microphone. The use of relatively large speakers to transduce low frequency sound sources, especially in music production, is becoming fairly common. Since a relatively massive membrane is unable to transduce high frequencies, placing a speaker in front of a kick drum is often ideal for reducing cymbal and snare bleed into the kick drum sound. [edit] Capsule design and directivity The shape of the microphone defines its directivity. Inner elements are of major importance and concerns the structural shape of the capsule, outer elements may be the interference tube. A pressure gradient microphone is a microphone in which both sides of the diaphragm are exposed to the incident sound and the microphone is therefore responsive to the pressure differential (gradient) between the two sides of the membrane. Sound incident parallel to the plane of the diaphragm produces no pressure differential, giving pressure-gradient microphones their characteristic figure-eight directional patterns. The capsule of a pressure microphone however is closed on one side, which results in an omnidirectional pattern. [edit] Microphone polar patterns Regarding directionality, omnidirectional microphones are pressure transducers, whereas all others are pressure gradient transducers or a combination between the two. Common polar patterns for microphones (Microphone facing top of page in diagram, parallel to page): Omnidirectional Subcardioid Cardioid Supercardioid Hypercardioid Bi-directional Shotgun A microphone's directionality or polar pattern indicates how sensitive it is to sounds arriving at different angles about its central axis. The above polar patterns represent the locus of points that produce the same signal level output in the microphone if a given sound pressure level is generated from that point. How the physical body of the microphone is oriented relative to the diagrams depends on the microphone design. For large-membrane microphones such as in the Oktava (pictured above), the upward direction in the polar diagram is usually perpendicular to the microphone body, commonly known as "side fire". For small diaphragm microphones such as the Shure (also pictured above), it usually extends from the axis of the microphone commonly known as "end fire".
Some microphone designs combine several principles in creating the desired polar pattern. This ranges from shielding (meaning diffraction/dissipation/absorption) by the housing itself to electronically combining dual membranes. [edit] Omnidirectional An omnidirectional microphone's response is generally considered to be a perfect sphere in three dimensions. In the real world, this is not the case. As with directional microphones, the polar pattern for an "omnidirectional" microphone is a function of frequency. The body of the microphone is not infinitely small and, as a consequence, it tends to get in its own way with respect to sounds arriving from the rear, causing a slight flattening of the polar response. This flattening increases as the diameter of the microphone (assuming it's cylindrical) reaches the wavelength of the frequency in question. Therefore, the smallest diameter microphone will give the best omnidirectional characteristics at high frequencies. The wavelength of sound at 10 kHz is little over an inch (3.4 cm) so the smallest measuring microphones are often 1/4" (6 mm) in diameter, which practically eliminates directionality even up to the highest frequencies. Omnidirectional microphones, unlike cardioids, do not employ resonant cavities as delays, and so can be considered the "purest" microphones in terms of low coloration; they add very little to the original sound. Being pressure-sensitive they can also have a very flat low-frequency response down to 20 Hz or below. Pressure-sensitive microphones also respond much less to wind noise than directional (velocity sensitive) microphones. [edit] Unidirectional A unidirectional microphone is sensitive to sounds from only one direction. The diagram above illustrates a number of these patterns. The microphone faces upwards in each diagram. The sound intensity for a particular frequency is plotted for angles radially from 0 to 360°. (Professional diagrams show these scales and include multiple plots at different frequencies. These diagrams just provide an overview of the typical shapes and their names.) [edit] Cardioids US664A University Sound Dymamic Supercardioid Microphone The most common unidirectional microphone is a cardioid microphone, so named because the sensitivity pattern is heart-shaped (see cardioid). A hyper-cardioid is similar but with a tighter area of front sensitivity and a tiny lobe of rear sensitivity. A super-cardioid microphone is similar to a hyper-cardioid, except there is more front pickup and less rear pickup. These three patterns are commonly used as vocal or speech microphones, since they are good at rejecting sounds from other directions. [edit] Bi-directional Figure 8 or bi-directional microphones receive sound from both the front and back of the element. Most ribbon microphones are of this pattern. [edit] Shotgun An Audio-Technica shotgun microphone Shotgun microphones are the most highly directional. They have small lobes of sensitivity to the left, right, and rear but are significantly more sensitive to the front. This results from placing the element inside a tube with slots cut along the side; wave-cancellation eliminates most of the off-axis noise. Shotgun microphones are commonly used on TV and film sets, and for field recording of wildlife. An omnidirectional microphone is a pressure transducer; the output voltage is proportional to the air pressure at a given time. On the other hand, a figure-8 pattern is a pressure gradient transducer; A sound wave arriving from the back will lead to a signal with a polarity opposite to that of an identical sound wave from the front. Moreover, shorter wavelengths (higher frequencies) are picked up more effectively than lower frequencies. A cardioid microphone is effectively a superposition of an omnidirectional and a figure-8 microphone; for sound waves coming from the back, the negative signal from the figure-8 cancels the positive signal from the omnidirectional element, whereas for sound waves coming from the front, the two add to each other. A hypercardioid microphone is similar, but with a slightly larger figure-8 contribution. Since pressure gradient transducer microphones are directional, at distances of a few centimeters of the sound source results in a bass boost. This is known as the proximity effect[2] [edit] Application-specific microphone designs A lavalier microphone is made for hands-free operation. These small microphones are worn on the body and held in place either with a lanyard worn around the neck or a clip fastened to clothing. The cord may be hidden by clothes and either run to an RF transmitter in a pocket or clipped to a belt (for mobile use), or run directly to the mixer (for stationary applications). A wireless microphone is one which does not use a cable. It usually transmits its signal using a small FM radio transmitter to a nearby receiver connected to the sound system, but it can also use infrared light if the transmitter and receiver are within sight of each other. A contact microphone is designed to pick up vibrations directly from a solid surface or object, as opposed to sound vibrations carried through air. One use for this is to detect sounds of a very low level, such as those from small objects or insects. The microphone commonly consists of a magnetic (moving coil) transducer, contact plate and contact pin. The contact plate is placed against the object from which vibrations are to be picked up; the contact pin transfers these vibrations to the coil of the transducer. Contact microphones have been used to pick up the sound of a snail's heartbeat and the footsteps of ants. A portable version of this microphone has recently been developed. A throat microphone is a variant of the contact microphone, used to pick up speech directly from the throat, around which it is strapped. This allows the device to be used in areas with ambient sounds that would otherwise make the speaker inaudible. A parabolic microphone uses a parabolic reflector to collect and focus sound waves onto a microphone receiver, in much the same way that a parabolic antenna (e.g. satellite dish) does with radio waves. Typical uses of this microphone, which has unusually focused front sensitivity and can pick up sounds from many meters away, include nature recording, outdoor sporting events, eavesdropping, law enforcement, and even espionage. Parabolic microphones are not typically used for standard recording applications, because they tend to have poor low-frequency response as a side effect of their design. [edit] Connectivity Electronic symbol for a microphone. [edit] Connectors The most common connectors used by microphones are: Male XLR connector on professional microphones¼ inch mono phone plug on less expensive consumer microphones3.5 mm (Commonly referred to as 1/8 inch mini) stereo (wired as mono) mini phone plug on very inexpensive and computer microphones Some microphones use other connectors, such as 1/4 inch TRS (tip ring sleeve), 5-pin XLR, or stereo mini phone plug (1/8 inch TRS) on some stereo microphones. Some lavalier microphones use a proprietary connector for connection to a wireless transmitter. Since 2005, professional-quality microphones with USB connections have begun to appear, designed for direct recording into computer-based software studios. [edit] Impedance matching Microphones have an electrical characteristic called impedance, measured in ohms (Ω), that depends on the design. Typically, the rated impedance is stated.[3] Low impedance is considered under 600 Ω. Medium impedance is considered between 600 Ω and 10 kΩ. High impedance is above 10 kΩ.
Most professional microphones are low impedance, about 200 Ω or lower. Low-impedance microphones are preferred over high impedance for two reasons: one is that using a high-impedance microphone with a long cable will result in loss of high frequency signal due to the capacitance of the cable; the other is that long high-impedance cables tend to pick up more hum (and possibly radio-frequency interference (RFI) as well). However, some equipment, such as vacuum tube guitar amplifiers, has an input impedance that is inherently high, requiring the use of a high impedance microphone or a matching transformer. Nothing will be damaged if the impedance between microphone and other equipment is mismatched; the worst that will happen is a reduction in signal or change in frequency response. To get the best sound in most cases, the impedance of the microphone must be distinctly lower (by a factor of at least five) than that of the equipment to which it is connected. Most microphones are designed not to have their impedance "matched" by the load to which they are connected; doing so can alter their frequency response and cause distortion, especially at high sound pressure levels. There are transformers (confusingly called matching transformers) that adapt impedances for special cases such as connecting microphones to DI units or connecting low-impedance microphones to the high-impedance inputs of certain amplifiers, but microphone connections generally follow the principle of bridging (voltage transfer), not matching (power transfer). In general, any XLR microphone can usually be connected to any mixer with XLR microphone inputs, and any plug microphone can usually be connected to any jack that is marked as a microphone input, but not to a line input. This is because the signal level of a microphone is typically 40-60 dB lower (a factor of 100 to 1000) than a line input. Microphone inputs include the necessary amplification circuitry to deal with these very low level signals. The exception to these comments is in the case of certain ribbon and dynamic microphones which are most linear when operated into a load of known impedance [4] [edit] Digital microphone interface The AES 42 standard, published by the Audio Engineering Society, defines a digital interface for microphones. Microphones conforming to this standard directly output a digital audio stream through an XLR male connector, rather than producing an analog output. Digital microphones may be used either with new equipment which has the appropriate input connections conforming to the AES 42 standard, or else by use of a suitable interface box. Studio-quality microphones which operate in accordance with the AES 42 standard are now appearing from a number of microphone manufacturers. [edit] Measurements and specifications A comparison of the far field on-axis frequency response of the Oktava 319 and the Shure SM58 Because of differences in their construction, microphones have their own characteristic responses to sound. This difference in response produces non-uniform phase and frequency responses. In addition, microphones are not uniformly sensitive to sound pressure, and can accept differing levels without distorting. Although for scientific applications microphones with a more uniform response are desirable, this is often not the case for music recording, as the non-uniform response of a microphone can produce a desirable coloration of the sound. There is an international standard for microphone specifications,[5] but few manufacturers adhere to it. As a result, comparison of published data from different manufacturers is difficult because different measurement techniques are used. The Microphone Data Website has collated the technical specifications complete with pictures, response curves and technical data from the microphone manufacturers for every currently listed microphone, and even a few obsolete models, and shows the data for them all in one common format for ease of comparison.[1]. Caution should be used in drawing any solid conclusions from this or any other published data, however, unless it is known that the manufacturer has supplied specifications in accordance with IEC 60268-4. A frequency response diagram plots the microphone sensitivity in decibels over a range of frequencies (typically at least 0–20 kHz), generally for perfectly on-axis sound (sound arriving at 0° to the capsule). Frequency response may be less informatively stated textually like so: "30 Hz–16 kHz ±3 dB". This is interpreted as a (mostly) linear plot between the stated frequencies, with variations in amplitude of no more than plus or minus 3 dB. However, one cannot determine from this information how smooth the variations are, nor in what parts of the spectrum they occur. Note that commonly-made statements such as "20 Hz–20 kHz" are meaningless without a decibel measure of tolerance. Directional microphones' frequency response varies greatly with distance from the sound source, and with the geometry of the sound source. IEC 60268-4 specifies that frequency response should be measured in plane progressive wave conditions (very far away from the source) but this is seldom practical. Close talking microphones may be measured with different sound sources and distances, but there is no standard and therefore no way to compare data from different models unless the measurement technique is described. The self-noise or equivalent noise level is the sound level that creates the same output voltage as the microphone does in the absence of sound. This represents the lowest point of the microphone's dynamic range, and is particularly important should you wish to record sounds that are quiet. The measure is often stated in dB(A), which is the equivalent loudness of the noise on a decibel scale frequency-weighted for how the ear hears, for example: "15 dBA SPL" (SPL means sound pressure level relative to 20 micropascals). The lower the number the better. Some microphone manufacturers state the noise level using ITU-R 468 noise weighting, which more accurately represents the way we hear noise, but gives a figure some 11 to 14 dB higher. A quiet microphone will measure typically 20 dBA SPL or 32 dB SPL 468-weighted. The state of the art has recently improved with the NT1-A microphone from Røde, which has a noise level of 5dBA. The maximum SPL (sound pressure level) the microphone can accept is measured for particular values of total harmonic distortion (THD), typically 0.5%. This is generally inaudible, so one can safely use the microphone at this level without harming the recording. Example: "142 dB SPL peak (at 0.5% THD)". The higher the value, the better, although microphones with a very high maximum SPL also have a higher self-noise. The clipping level is perhaps a better indicator of maximum usable level, as the 1% THD figure usually quoted under max SPL is really a very mild level of distortion, quite inaudible especially on brief high peaks. Harmonic distortion from microphones is usually of low-order (mostly third harmonic) type, and hence not very audible even at 3-5%. Clipping, on the other hand, usually caused by the diaphragm reaching its absolute displacement limit (or by the preamplifier), will produce a very harsh sound on peaks, and should be avoided if at all possible. For some microphones the clipping level may be much higher than the max SPL. The dynamic range of a microphone is the difference in SPL between the noise floor and the maximum SPL. If stated on its own, for example "120 dB", it conveys significantly less information than having the self-noise and maximum SPL figures individually. Sensitivity indicates how well the microphone converts acoustic pressure to output voltage. A high sensitivity microphone creates more voltage and so will need less amplification at the mixer or recording device. This is a practical concern but is not directly an indication of the mic's quality, and in fact the term sensitivity is something of a misnomer, 'transduction gain' being perhaps more meaningful, (or just "output level") because true sensitivity will generally be set by the noise floor, and too much "sensitivity" in terms of output level will compromise the clipping level. There are two common measures. The (preferred) international standard is made in millivolts per pascal at 1 kHz. A higher value indicates greater sensitivity. The older American method is referred to a 1 V/Pa standard and measured in plain decibels, resulting in a negative value. Again, a higher value indicates greater sensitivity, so −60 dB is more sensitive than −70 dB. [edit] Measurement microphones Some microphones are intended for use as standard measuring microphones for the testing of speakers and checking noise levels etc. These are calibrated transducers and will usually be supplied with a calibration certificate stating absolute sensitivity against frequency. [edit] Microphone calibration techniques [edit] Pistonphone apparatus A pistonphone is an acoustical calibrator (sound source) using a closed coupler to generate a precise sound pressure for the calibration of instrumentation microphones. The principle relies on a piston mechanically driven to move at a specified rate on a fixed volume of air to which the microphone under test is exposed. The air is assumed to be compressed adiabatically and the SPL in the chamber can be calculated from the adiabatic gas law, which requires that the product of the pressure P with V raised to the power gamma be constant; here gamma is the ratio of the specific heat of air at constant pressure to its specific heat at constant volume. The pistonphone method only works at low frequencies, but it can be accurate and yields an easily calculable sound pressure level. The standard test frequency is usually around 250 Hz. [edit] Reciprocal method This method relies on the reciprocity of one or more microphones in a group of 3 to be calibrated. It can still be used when only one of the microphones is reciprocal (exhibits equal response when used as a microphone or as a loudspeaker). [edit] Microphone array and array microphones Main article: Microphone array A microphone array is any number of microphones operating in tandem. There are many applications: Systems for extracting voice input from ambient noise (notably telephones, speech recognition systems, hearing aids)Surround sound and related technologiesLocating objects by sound: acoustic source localization, e.g. military use to locate the source(s) of artillery fire. Aircraft location and tracking.High fidelity original recordings Typically, an array is made up of omnidirectional microphones distributed about the perimeter of a space, linked to a computer that records and interprets the results into a coherent form. [edit] Microphone windscreens Windscreens are used to protect microphones that would otherwise be buffeted by wind or vocal plosives (from consonants such as "P", "B", etc.). Windscreens are often made of soft open-cell polyester or polyurethane foam because of the inexpensive, disposable nature of the foam. Finer windscreens are made of thin plastic screening held out at a distance from the diaphragm by a framework or cage fitted to the microphone body. Pop filters or pop screens are used in controlled studio environments to keep plosives down when recording. Foam windscreens are integral to some microphone designs such as the Shure SM58 which has a thin foam layer just inside the wire mesh ball enclosing the diaphragm. Optional windscreens are often available from the manufacturer and third parties. A very visible example of optional accessory windscreen is the A2WS from Shure, one of which is fitted over each of the two SM57s used on the United States Presidential lectern.[6] Large, hollow "blimp" or "zeppelin" windscreens are used to surround boom microphones for location audio such as nature recording, electronic news gathering and for film and video shoots. They can cut wind noise by as much as 25 dB, especially low-frequency noise. A refinement of the blimp windscreen is the addition of a synthetic furry cover which can cut wind noise down by a further 12 dB.[7] Vocalists often use windscreens on handheld microphones to cut plosive breath noise that involve sharp outward airflow from the mouth. The necessity of a windscreen increases the closer a vocalist brings the microphone to their lips. Singers can be trained to soften their plosives, in which case they don't need a windscreen for any reason other than wind. Windscreens are used extensively in outdoor concert sound and location recording where wind is an unpredictable factor. Highly directional microphones benefit the most from windscreens, more so than omnidirectional mics which aren't as vulnerable to wind noise. One disadvantage of windscreens is that the microphone's high frequency response is attenuated by a small amount relative to how dense the protective layer is. Another disadvantage is that windscreens are often fragile, lightweight and/or small, making it easy to damage or lose them. Poorly fitted windscreens can slip to expose microphone porting to wind action and can fall off completely. The polyurethane foam deteriorates over time, requiring replacement in older microphones undergoing refurbishment. Windscreens collect dirt and moisture in their open cells and must be cleaned from time to time to prevent high frequency loss, bad odor and unhealthy conditions for the artist. On the other hand, a major advantage of concert vocalist windscreens is that one can quickly change to a clean windscreen between artists, reducing the chance of transferring germs. Windscreens of various colors can be used to distinguish one microphone from another on a busy, active stage. [edit] See also Electronics Portal Loudspeaker (the inverse of a microphone)Hydrophone (microphone for underwater use)Geophone (microphone for use within the earth)Ionophone (plasma-based microphone)Microphone connectorMicrophone practiceA-weightingButton microphoneITU-R 468 noise weightingNominal impedance — Information about impedance matching for audio componentsSound pressure levelWireless microphoneXLR connector — The 3-pin variant of which is used for connecting microphones [edit] References ^ "Electret Microphone Turns 40"^ http://www.tonmeister.ca/main/textbook/node473.html Introduction To Sound Recording Geoff Martin^ International Standard IEC 60268-4^ Robertson, A. E.: "Microphones" Illiffe Press for BBC, 1951-1963^ International Standard IEC 60268-4^ http://www.shure.com/ProAudio/Products/Accessories/us_pro_A2WS-BLK_content^ http://www.rycote.com/products/windshield/