Here are the tags you'll need. The BGSOUND SRC tag is for Internet Explorer, the Embed tag is for Netscape Navigator:

<BGSOUND SRC="sound.wav" LOOP=INFINITE>
<EMBED SRC="sound.wav" AUTOSTART="true" HIDDEN="true" LOOP="true">

This will create an infinitely looping sound for both IE and Netscape.

To create a sound that doesn't loop:

<BGSOUND SRC="sound.wav" LOOP=0>
<EMBED SRC="sound.wav" AUTOSTART="True" HIDDEN="True" LOOP="false">

With the later versions of Internet Explorer, however, the above tag will give IE users two sound controls. To avoid that, add the NOEMBED and closing /NOEMBED tag around the BGSOUND SRC tag:

<NOEMBED>
<BGSOUND SRC="sound.wav" LOOP=0>
</NOEMBED>
<EMBED SRC="sound.wav" AUTOSTART="True" HIDDEN="True" LOOP="false">

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