Here's what I'm using:
<audio autoplay>
<source src="/static/sound/SOUND.mp3" type="audio/mpeg">
<source src="/static/sound/SOUND.ogg" type="audio/ogg">
<source src="/static/sound/SOUND.wav" type="audio/wav">
<source src="/static/sound/SOUND.aiff" type="audio/x-aiff">
<object>
<param name="autostart" value="true">
<param name="src" value="/static/sound/SOUND.mp3">
<param name="autoplay" value="true">
<param name="controller" value="false">
<embed src="/static/sound/SOUND.mp3" controller="false" autoplay="true" autostart="true" type="audio/mpeg"></embed>
</object>
</audio>
I provide the same audio clip in MP3, OGG, WAV, and AIFF and then let the browser pick which it wants to play. The audio
tag is for HTML5, the object
tag is for older systems, and embed
works on some systems not supporting the object tag.
I put this together from some information on a few websites, but unfortunately I've forgotten the URL.
UPDATE
I've since switched to using howler.js for this stuff. It automatically deals with all the cross-browser issues related to sound. Unfortunately it doesn't support IE 6-8, but I've given up supporting those any way.