Javascript - change audio file voice with pitch or filters like

The code below takes an mp3 file and play it, what i would like to do is to change in some way the pitch ( for example of the voice) to return a strange/weird voice instead of the normal one.

Is it possible in any way?

 var src
  , fftSize = 1024
  , audio = new Audio()
  , ac = new webkitAudioContext()
  , comp = ac.createDynamicsCompressor()
  , bar = document.querySelector('.bar')
  , url = 'http://media.tts-api.com/2aae6c35c94fcfb415dbe95f408b9ce91ee846ed.mp3';

  audio.src = url;
  comp.ratio.value = 0.95;

  audio.addEventListener('canplaythrough', function() {
    src = ac.createMediaElementSource(audio);
    src.connect(comp);
    comp.connect(ac.destination);
    audio.play();
  }, false);