code: function changeSample() {
      document.getElementById('play').disabled = true;
      document.getElementById('stop').disabled = true;
      soundUrl = document.getElementById("sample_no").value;
      if (typeof sound != 'undefined' && sound.isPlaying) {
          sound.stop(0);
          sound.isPlaying = false;
      }
      loadSample(soundUrl, assignSample2SoundBuffer);
  }
docs: function to change sample from select box