I would like to ask if someone could help me with ring modulation using javascript

Here is my code. I am not sure if I am doing this right. On start button it only plays a oscillator with gain. No mix with audio file.

I tried do something like this GitHub source

Thanks

function audioFileLoader(fileDirectory, impulseFileDirectory) {
  var audioContext = new AudioContext();
  var soundObj = [];
  soundObj.fileDirectory = fileDirectory;
  soundObj.impulseFileDirectory = impulseFileDirectory;

  // buffer loader code
  var getSound = new XMLHttpRequest();
  getSound.open("GET", soundObj.fileDirectory, true);
  getSound.responseType = "arraybuffer";
  getSound.onload = function() {
      audioContext.decodeAudioData(getSound.response, function(buffer) {
          soundObj.soundToPlay = buffer;
      });

  }

  getSound.send();

  soundObj.play = function() {

    var source = audioContext.createBufferSource();
    source.buffer = soundObj.soundToPlay;

    var oscillator = audioContext.createOscillator();
    oscillator.type = 'sine';
    oscillator.frequency.value = 500;

    var gainNode = audioContext.createGain();
    gainNode.gain.value = 0.5; 
     
    oscillator.connect(gainNode);
    source.connect(gainNode);  
    gainNode.connect(audioContext.destination);

    oscillator.start(audioContext.currentTime);
  };

   return soundObj;
};

var example = audioFileLoader("audio/AcGtr.wav");

document.getElementById('ringmodulation').addEventListener("click", example.play, 
false);