You can use the ADE (ade.js) included with the SDK to check for any js errors using a desktop browser. JS errors will be reported on Android in logcat as well. However depending on the phone this might be hard to spot.
Checking your code with the ADE in a desktop browser reveals that:
Syntax error at 22, Unexepected ;
There is actually one ( too much. Correcting that, and it works:
var sound = new AR.Sound("assets/sec.mp3", { onLoaded : function(){sound.play();}, onError : function(){ // alert the user that the sound file could not be loaded }, });
Wolfgang Damm