The WCAG 1.0 checkpoints and Section 508 federal mandates that require a text equivalent for every nontext element apply not just to graphic elements but also to audio material including audio material that's not part of a video. We have already seen how the audio portion of a video display can be made accessible to users who will not hear the sounds. These may be users with hearing impairments but are just as likely to include those who are accessing the Web by means of a public computer station, such as those provided in libraries, schools, and many community recreation centers. Millions of people use public access technology; although some of these facilities may provide headphones for private listening, a developer who is aiming for maximum accessibility will not depend on sound alone to convey important information.
If information is provided as voice narration in a stand-alone audio file, then a text transcript is the most straightforward accessibility solution. Crafting alternatives for musical content requires a bit more thought, however. What is the purpose of the music? Is it simply decorative, akin to elevator music for the site? If so, a simple ALT text attached to the .wav file or other sound element (alt="background music", for example) should suffice, although you must also provide the means for users to choose to hear the mu-sic or not, as we mentioned in our earlier discussion about giving users control over media playback.
Now, if the purpose is to set a tone or mood in which the rest of the content is placed, a longer description of the type of music, its speed, and its other qualities would be appropriate. Such a description will help nonlistening visitors to have an experience more equivalent to the one you intend. Similarly, in cases where sounds other than music contribute to the general experience, description is required.
But where music or other sound is truly integral to the presentation, it is worth giving careful thought to the notion of "equivalence." Author M. D. Coverley submitted a complex multimedia work for publication in the journal Currents in Electronic Literacy. The journal requires authors to follow WCAG. In the passage below, Coverley explains how she thought through the issue of music as she reworked her Mirror of Annihilated Simple Souls, originally done in Flash:
. . . [T]he first job was to survey the image, motion, and sound elements and determine how to replace each of them with a representation in a different medium. The sound was the easiest, so I began with that. But here, immediately, . . . aesthetic considerations arose. The MIDI sequence . . . is a 16th century air from the Court of Henry the 8th. While it was a simple enough matter to provide an explanation of the harpsichord-like sound and the articulated, antique notes, it was less clear that the "text" was in any way an "equivalent." Unless the reader could, in fact, imagine a dark-light melody from five hundred years ago, then the effect [of the combined sounds, images, and text] became much less resonant. I began to see, in a way that had not been evident to me previously, that multimedia writing depends on a carefully constructed oscillation between the visual, the aural, and the textual. . . . It wasn't so critical that a reader could actually hear the sound in and of itself, yet the sound acted in concert with other sensory signifiers. The problem I faced in making the sound accessible to the hearing impaired was that the images and text relied upon the sound for completion.
 From M. D. Coverley, "The White Wall: Reframing the Mirror," Currents in Electronic Literacy Fall 2001 (5). Accessed June 28, 2002. Current link is http://currents.curl.utexas.edu/archives/fall01/fall01/coverley.html.
Alternative Audio Examples
Let's try a couple of simpler examples. The first is a short and simple audio clip that demonstrates the song of the golden-cheeked warbler. Figure 13-7 shows the page. Here's the code below.
Figure 13-7. Screen shot illustrating how the code for the birdsong will render on the page.
<html><head><title>warblerpage</title></head> <body> <table border=0 width="85%"> <tr><td> . . . <tr> <td>Activate this link to listen to the call of the golden-cheeked warbler. </font><a href="warbler.wav"> <img src="/books/3/135/1/html/2/warbler.jpg" ALT="Golden-cheeked warbler photo linked to a recording of Songtype B, described above"></a> </tr> </table> </body> </html>
The code creates a graphic link from the picture of the bird to a sound file of the bird's song. As the image for the sound file is accessed, the ALT message appears briefly on the screen and is made available to assistive devices. In this case, the ALT text describes the picture and suggests how the file sounds when it plays. All the information is easily delivered to those who are not seeing the page, as well as those who are not hearing it.
But suppose we want to include more information. In addition to a recording of the warbler's call, we want to include a longer voiceover describing the bird's habitat. In this case, we will also need a link to an HTML file that contains a complete text transcript of the habitat description. Theoretically, this can be done either through a direct link on the screen or by supplementing the ALT text for the warbler.jpg image with a longdesc attribute containing the name of the transcript file. Because the longdesc attribute has not been well supported until quite recently (as we noted in Chapter 9), we include both options in the next example.
<html><head><title>warblernarrativepage</title></head> <body> <table border=0 width="85%"> <tr><td> . . . <tr> <td>Activate this link to listen to the call of the golden-cheeked warbler and a description of its habitat. <a href="warblernarration.wav"><img src="/books/3/135/1/html/2/warbler.jpg" alt="Warbler photo activates audio narration" longdesc="warblernarration.html"></a></td> </tr> <tr> <td>Not using audio? Read the <a href="warblernarration.html"> full text of the warbler narration</a></td> </tr> </table> </body> </html>
Figure 13-8 shows how the code above will render.
Figure 13-8. Screen shot depicting how the revised code will render on the page.
The alt tag describes the image and the fact that it links to an audio file. The longdesc attribute is also associated with the image, indicating the availability of a text transcript of the audio file. In addition, the alternative is explicitly offered by means of the sentence "Not using audio?" with a link to the text transcript. Note that this can be accomplished as well by associating a d-link with the longdesc attribute. This practice is not widely accepted, however. In part, the lack of acceptance may come from the fact that, as the longdesc attribute becomes fully supported by browsers and assistive devices, the d-link will no longer be necessary. Finally, the purpose is simply to use the best tools to ensure that important content is available to everyone. As your commitment to making accessible multimedia grows, we believe you will find a related growth in your creative thinking about the associated challenges. How, for example, can you create an accessible experience for something as visual as animation? Let's find out.