adjusting volume HTML5 web audio

code samples on how to adjust the volume of web audio using the gain node useful for reducing noise and loud sound output i included comments to show a bit of guidance on how it works.
sound = function sound(url, opt) {

    var loop = opt.loop || false;

 // Create an AudioContext instance for this sound

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

 // Create a buffer for the incoming sound content

 var source = audioContext.createBufferSource();
 // source got replaced with gain node here to accommodate volume adjustment
 var gainNode = audioContext.createGain()

 gainNode.gain.value = 0.05 // 20 % noise,



 // Create the XHR which will grab the audio contents

 var request = new XMLHttpRequest();

 // Set the audio file src here'GET', url, true);

 // Setting the responseType to arraybuffer sets up the audio decoding

 request.responseType = 'arraybuffer';

 request.onload = function() {

   // Decode the audio once the require is complete

   audioContext.decodeAudioData(request.response, function(buffer) {

     source.buffer = buffer;

     // Connect the audio to source (multiple audio buffers can be connected!)


     // now instead of connecting to aCtx.destination, connect to the gainNode


     // Simple setting for the buffer

     source.loop = loop;

     // Play the sound!


   }, function(e) {

     console.log('Audio error! ', e);



 // Send the request which kicks off