test.html

<!DOCTYPE html>
<html>
<head>
<script>
function playAudio() {
	var a = new Audio();
	a.src = "audio.wav"; 
	a.play();
}
</script>
</head>
<body onload=" window.audio = document.getElementById('audio') ">

<audio id="audio" preload="auto">
	<source src="audio.wav"></source>             
</audio> 

<input type="button" onclick="playAudio()" value="play sound">

</body>
</html>