I think the easiest way would be just add Audio Web API and something like this into the im_chat.js

var beep = function(duration, type, finishedCallback) {

if (!(window.audioContext || window.webkitAudioContext)) {

throw Error("Your browser does not support Audio Context.");

}

duration = +duration;

// Only 0-4 are valid types.

type = (type % 5) || 0;

if (typeof finishedCallback != "function") {

finishedCallback = function() {};

}

var ctx = new (window.audioContext || window.webkitAudioContext);

var osc = ctx.createOscillator();

osc.type = type;

osc.connect(ctx.destination);

osc.noteOn(0);

setTimeout(function() {

osc.noteOff(0);

finishedCallback();

}, duration);

};