var oReq = new XMLHttpRequest();
oReq.open( 'GET', fileName, true);
oReq.responseType = 'arraybuffer';
oReq.onload = function (oEvent) {
var arrayBuffer = oReq.response;
};
oReq.send(null);
var context = new AudioContext();
var a = document.createElement( 'audio' );
a.src = trackName;
a.play();
var audioSource = context.createMediaElementSource( a );
audioSource.connect( context.destination );