代码
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>无标题文档</title>
<script>

if (window.navigator.userAgent.indexOf("MSIE")>=1)
//如果浏览器为IE
{
        document.write('<object id="MediaPlayer1" width="0" height="0" classid="CLSID:6BF52A52-394A-11d3-B153-00C04F79FAA6" codebase="http://activex.microsoft.com/activex/controls/mplayer/en/nsmp2inf.cab#Version=6,4,5,715" align="baseline" border="0" standby="Loading Microsoft Windows Media Player components..." type="application/x-oleobject"> <param name="invokeURLs" value="0" /> <param name="autostart" value="1" /> <param name="url" value="1.mp3" /></object>');
}
else //如果浏览器为Firefox
{    if (window.navigator.userAgent.indexOf("Firefox")>=1)
    {
    document.write('<embed type="application/x-mplayer2" pluginspage="http://www.microsoft.com/windows/mediaPlayer/" id="player" src="1.mp3" name="player2" width="0" height="0" volume="100"></embed>');
        }
    }

</script>
</head>

<body>


</body>
</html>