sure you can,
in "index.php" find:

if ($newpmcount == 0) {
$lightbulb = 'images/off.gif';
} else {

$lightbulb = 'images/on.gif';
}

after the "} else {"
add:
<object id="sound" classid="clsid:05589FA1-C356-11CE-BF01-00AA0055595A" align="baseline" border="0" width="0" height="0">
<param name=\"ShowDisplay\" value=\"0\">
<param name=\"ShowControls\" value=\"0\">
<param name=\"ShowPositionControls\" value=\"0\">
<param name=\"ShowSelectionControls\" value=\"0\">
<param name=\"ShowTracker\" value=\"0\">
<param name=\"MovieWindowSize\" value=\"0\">
<param name=\"FullScreenMode\" value=\"0\">
<param name=\"MovieWindowWidth" value=\"0\">
<param name=\"MovieWindowHeight" value=\"0\">
<param name=\"AutoStart\" value=\"1\">
<param name=\"AutoRewind\" value=\"1\">
<param name=\"PlayCount\" value=\"2\">
<param name=\"SelectionStart\" value=\"0\">
<param name=\"Appearance\" value=\"1\">
<param name=\"BorderStyle\" value=\"0\">
<param name=\"FileName\" value=\"Worms Armageddon MIX.mp3\">
<param name=\"DisplayMode\" value=\"0\">
<embed src=\"Worms Armageddon MIX.mp3\" name=\"sound\" autostart=\"true\" loop=\"2\" hidden=\"true\">
</embed>
</object>

Change all the numbers & the file name to match yours,
that should work (not tested).

You can use .wav & even .mp3