There are many roles for sound in a Web -based instructional resource. Your users might hear, for example, an animal call, a piece of music, or pronunciation in a foreign language. Most multimedia computers arrive with the hardware and software users need to hear audio files. Audio files can be distributed in several formats. The AU format, developed by Sun Microsystems, is perhaps the oldest, and tools exist to play AU files on just about every kind of computer. In the Macintosh world, the AIFF format predominates, while virtually every Windows PC can deal with WAV sound files.
Unfortunately, sound standardization has yet to arrive on the Web . The HTML language specification made provisions for certain types of sound (the way GIF and JPG formats were provided for), but platform incompatibilities have delayed implementation.
Newer versions of browsers now include the functionality that allows them to play various types of audio files. In older browswers, "helper applications" were needed. Sound files in the above formats must download to the user's hard drive before being played by the browser or helper application. The larger the file and the slower the connection, the longer the download will take.
"Streaming audio" formats also exist on the Web . Streaming technologies use "buffering" to cope with network transmission inconsistencies. The incoming file is allowed to accumulate in a temporary holding area -- the buffer -- and plays from there. Streamed audio plays as it arrives; users equipped with the appropriate plug-ins and/or software won't need to wait for the entire file to download before hearing the sound. Streamed audio is still bandwidth-intensive, however. Users with slow Internet connections may experience gaps in the sound.
Typically, users need a player for the format in which the streaming audio was encoded. One example of a streaming format that is widely used on the Web is RealAudio" pioneered by RealNetworks. Their site provides players and production tools.
When you incorporate sound in your Web resource, provide links to sources for necessary plug-ins. Wherever possible, offer alternative pathways for acquiring the information that is presented in the sound files.
