Association of Science - Technology Centers
About ASTC
About Science Centers
Annual Conference
Exhibition Services
Professional Development
Resource Center
  Accessible Practices
Museums' Legal Obligations
Disability Rights Movement
Access Advisors
Access Survey
Access Plan
Best Practices
Behind the Scenes
Links & Publication
Equity and Diversity
Making the Case
Science Center Planning
Visitor Studies
Youth Programs
Products and Services
Older Adults in Science Centers

Resource Center

Accessible PracticesBest PracticesCaptioning
Symbol for closed captioning. What Captioning Is and Who Uses It

Captioning is the transcription and display of dialogue and other auditory information, such as on- and off-screen sound effects, music, and laughter. In museums, captioning is used in videos and films, live performances and demonstrations, planetarium shows, lectures, web sites.

Captioning benefits more than people who are deaf or hard of hearing. In loud or crowded exhibition halls, captioned videos allow sighted visitors to read what they cannot hear. Captions also benefit new readers and people who are learning English as a second language.

Be sure to advertise the availability of captioning in brochures and on your web pages. Use appropriate signage and symbols in the museum to alert potential users to where captioning is available and, if necessary, where they can procure equipment for viewing captioning.

Museums cannot charge visitors for use of caption viewing equipment. If options are available, staff should always ask visitors which device they need or prefer. Also, staff who dispense captioning equipment need to be trained in its use and maintenance.


Open captions appear on-screen, whereas closed captions only appear when an electronic device called a decoder is activated by the user. Televisions made for sale in the U.S. since 1993 are required to have a built-in decoder.

Captioning transmitted live is called realtime or online captioning. Some interpreter service agencies provide computer-aided real-time reporting (CART), a realtime captioning service for live performances. Captioning that is recorded and then shown at other times is called offline captioning.


The Captioning FAQ ( offers examples of what captioning looks like and explains different kinds of captioning.

Equipment Needed

For offline captioning of a program, you may need

  • SVHS copy of the master video or other recorded program
  • Transcript of dialogue for the program (not required, but can significantly reduce the cost of having the program captioned)
  • Display unit (will need captioning decoder if closed captioned)

For online captioning of a program, you may need

  • Trained captioning stenographer (a trained captioner should be able to provide the equipment necessary for captioning a live program)
  • Transcript for the program (could be helpful to the captioner)

Where to Get the Equipment You Need

Closed Captioning Web
The Closed Captioning Web provides a comprehensive list of captioning service agencies under the heading "Services." There is detailed information about laws and cases pertaining to captioning, captioned movies, links related to hearing impairment and captioning.

Links Related to Captioning

Behind the Scenes
Bridget Shea, Theater Manager: Making Large-Format Theaters and Planetariums Accessible.

Caption Center
The Caption Center is the world's first captioning agency and a nonprofit service of WGBH Public Television in Boston, Massachusetts. This organization captions videos, films, and television programs and provides information on terminology, technology, laws, and recent developments in the field.

"Captioning Planetarium Programs for the Hearing Impaired." Bridget M. Shea. Planetarian. Vol. 23, no. 3, September 1993.
Bridget Shea describes the process and equipment used for captioning at the Davis Planetarium, Maryland Science Center.

Closed Captions for Web Multimedia
Microsoft Accessibility describes technology used to caption multimedia elements on the Internet. This site explains Synchronized Accessible Media Interchange (SAMI), a format used to add captions and audio descriptions to multimedia on the Internet. The site includes downloads and demonstrations.

Closed Captioning Web
The Closed Captioning Web provides a comprehensive list of captioning service agencies under the heading, "Services." There is detailed information about laws and cases pertaining to captioning, captioned movies, and links related to hearing impairment and captioning.

Gary Robson's Closed Captioning FAQ
This site provides in-depth information on captioning laws, terminology, procedures, and equipment. Included are guidelines to help users choose what kinds of captioning best serve their purposes and hints on how to select a captioning service agency for real-time captioning.

Media Access Generator (MAGpie)
Using MAGpie, authors can add captions to three multimedia formats: Apple's QuickTime, the World Wide Web Consortium's Synchronized Multimedia Integration Language (SMIL), and Microsoft's Synchronized Accessible Media Interchange (SAMI) format. MAGpie can also integrate audio descriptions into SMIL presentations. You can download MAGpie from this site free of charge.

National Captioning Institute (NCI)
NCI is a nonprofit organization established to provide captions for television programming. The NCI site provides information on terminology, laws, and the process of captioning.

History of Captioning

In the beginning, there were silent movies – a form of captioned media where everyone, hard of hearing or not, read dialogue on screen. The advent of talking pictures, generally considered a giant leap forward in entertainment, excluded generations of movie goers who were hard of hearing or deaf. Captioning for first-run movies did not return to the silver screen until the 1998 showings of Titanic, Mask of Zorro, and The Jackal.

The story of captioning as a service for people who are deaf or hard of hearing began on August 5, 1972, when Julia Child, The French Chef, taught viewers to make a special chicken recipe. This broadcast from WGBH studios in Boston has been immortalized not because of the exquisite entrée, but because of its significance to communication. The French Chef provided Americans who are deaf and hard of hearing their first opportunity to enjoy the audio portion of a national television program through the use of open captions.

The Public Broadcasting System (PBS), with federal funding, took the lead in captioning broadcast programming in the 1970s. The Caption Center, a service of WGBH Boston, captioned programs such as The Captioned ABC News, a late-night rebroadcast carried by more than 190 PBS stations, and Zoom, a children's series.

The first demonstration of closed captioning took place in 1971 at the National Conference on Television for the Hearing Impaired in Nashville, Tennessee. Successful testing prompted the U.S. Federal Communications Commission (FCC) to set aside line 21 for the transmission of closed captions in 1976. PBS and the Caption Center received federal funding to develop caption-editing consoles that would be used to caption prerecorded programs, encoding equipment that broadcasters and others would use to add captions to their programs, and prototype decoders.

On March 16, 1980, the National Captioning Institute broadcast the first closed captioned television series. Programs such as The ABC Sunday Night Movie, The Wonderful World of Disney, and Masterpiece Theater whetted the appetites of audience members for more captioned television. IBM became the first company to closed caption its commercials. The following year, closed captions spread to home videos. In 1982, realtime captioning hit the scene during live broadcasts of the Sugar Bowl and the Academy Awards. Early captioning efforts were laborious and costly because there were few commercial tools available for captioning.

Two laws significantly impacted the spread of captioning. The Television Decoder Circuitry Act of 1990 mandated that by mid-1993 all new television sets 13 inches or larger manufactured for sale in the U.S. must contain caption decoding technology. The Telecommunications Act of 1996 required that "video programming first published or exhibited after the effective date of such regulations is fully accessible through the provision of closed captions." The 1996 Act empowered the FCC to interpret and enforce it. The FCC mandated an eight-year phase-in starting on January 1, 1998, for captioning of "new" programming (programs that air for the first time after the ruling takes effect). By January 1, 2006, 95 percent of all new television programming must be captioned. The FCC did not create a phase-in for "old" programming, but required that by January 1, 2006, 75 percent of programming that originally aired before the Act must be captioned.

Developments in technology have both facilitated captioning and challenged it to grow in new directions. The Caption Center collaborated with Microsoft to make the CD-ROM encyclopedia Encarta 98 accessible in 1997. The Caption Center also developed a software utility that allows realtime staff to send simultaneous data streams for closed captioning and web site URLs for the benefit of WebTV users. Many captioning companies are working hard to ensure that Digital Television has high-quality captioning.

In a relatively short period of time, the demand for captioning has driven its availability from a few television programs to a ubiquitous service in various media. Captioning is now provided for movies, television programs, videos, musical and theater performances, lectures, government proceedings, planetarium shows, meetings and conferences. The demand for captioned programming of all kinds should drive science centers and museums to utilize this service to tap into the responsive and powerful market of visitors who are hard of hearing or deaf.

Sources for History of Captioning:,,


This web site is not intended to offer legal, architectural, engineering, or similar professional advice. Refer specific questions to an attorney or an ADA authority.

return to top
About ASTC | About Science Centers | Annual Conference | Exhibition Services
  Professional Development | Publications | Resource Center | ASTC Home  

ASTC Home Find a Science Center