Sound works differently in the two major browsers. You would need to write to different branches of code, one for IE and one for netscape. IE uses the BGSound tag to embed sounds. You would embed the sound, name it and set it to zero volume, loop=0. Netscape uses the embed tag though Netscape 6 will use the Object tag. You would do the same thing embed the sound, loop it once and set the volume to zero.
When you go to play the sound Netscape has a sound object you can access through liveconnect its as simple as soundname.run(). With IE you have to access it through Windows Media player which is a little more involved but it still comes down to soundname.run(). You can find examples on embedding sound at both Software companies sites. Microsoft's is msdn.microsoft.com and Netscape's is developer.netscape.com.
Sound will be tricky until both browsers open the sound object to scripting and use sound through the <object> tag. The <object> tag will eventually replace the bgsound and embed tags both of which are proprietary and don't exist in the HTML specification. Once <object> is included properly in the browsers you will be able to access sounds as easy as you do images (note: the object tag is also slated to replace the <img> tag in the future) today.
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