playAudio

var ctx = {};
ctx.URL = window.URL || window.webkitURL;
ctx.blobSrc = null;
ctx.audio = new Audio();

ctx.playAudio = function(blob) {
    if (ctx.blobSrc != null) {
        ctx.audio.pause();
        ctx.URL.revokeObjectURL(ctx.blobSrc);
    }
    ctx.blobSrc = ctx.URL.createObjectURL(blob);
    ctx.audio.src = ctx.blobSrc;
    ctx.audio.load();
    ctx.audio.play();
  }