alex72bel,
<!DOCTYPE HTML>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js"></script>
<style type="text/css">
.show {
display: none;
}
</style>
</head>
<body>
<script>
$(function(){
setTimeout(function() {
$('.show').show();
$('#aaa').attr({src : 'http://rem-31.ru/SCHelkajut_palccami.mp3'})
},20000);
setTimeout(function() {
$('.show').hide();
},30000)});
</script>
<audio src="" volume="100" autoplay id='aaa'></audio>
<div class='show'><a id="trigg1" href="javascript:void(0);"><img src="/images/vyzvat_zamershhika.png" height=""/></a></div>
</body>
</html>