Audio is the reading of text out loud by a professional narrator or voice synthesizer. Screen readers are often connected to voice synthesizers for people who cannot read computer text.
It is important that the audio capture all of the meaning of the original publication. All graphics and non-text items must be fully explained in text.
So that an audio program can be heard easily from any location it is typically packaged on cassette tape for use in portable cassette players. The tapes use index tones to identify each part of the table of contents.
The standard format is 2-track audio which provides programming on each side of a cassette tape for playback on any commercially available cassette tape player. (A number of organizations distribute 4-track audio to increase the amount of programming that can be put on a single cassette but this format requires special playback machines).
Audio delivered on cassette tape remains a popular method of delivery because of the portability and low cost of small cassette players. However, other audio playing devices have become just as mobile such as portable CD and MP3 players.
Another emerging audio technology is DAISY, which stands for "Digital Audio-based Information System". Using this technology, a publication in audio format can be "tagged" so the user can quickly and easily navigate the publication's pages, chapters, sections and other components without the need to rewind or fast forward. It is similar to music CDs where the user can select a particular track with the touch of a button.
DAISY is still a relatively new technology. More information
is available on the DAISY Web site.
Of course, there are also an increasing number of audio formats for the Internet. Among them is MP3 (the third generation of "Moving Picture Experts Group" electronic files) which has the ability to compress large video and audio material into small files that download faster. The ability to add captions, alternate language tracks and described video tracks to common Web-based multimedia formats, such as Apple's QuickTime, Microsoft Windows Media and RealNetworks' media, is possible using new Web languages such as the "Synchronized Multimedia Integration Language" (SMIL) from the W3C.
For more information, visit the W3C Web site.
The Audio format is used to facilitate access to printed publications for people who are blind or have low vision. It also removes the challenge of interpreting computer files that contain graphics, have multiple columns and other complicated design components that are unfriendly to screen reading devices.
In addition, Audio can be used on Web Sites as an alternative
to text (making certain a text version of the audio is also
posted).
It is also recommended for all users when reading print is not
possible, such as when driving, or is cumbersome, as would be the
case when touring exhibits.
Finally, this format is appropriate to enhance comprehension
for people with learning disabilities or low literacy
skills.