code: function(track) {
    var request = new XMLHttpRequest()
    request.open('GET', 'sounds/' + track + '.wav', true)
    request.responseType = 'arraybuffer'
    request.onload = function() {
      context.decodeAudioData(request.response, function(buffer) {
        var createNode = function() {
          var node = context.createBufferSource()
          node.buffer = buffer
          node.connect(context.destination)
          return node
        }
        soundBank[track] = { createNode: createNode }
      })
    }
    request.send()
  }
docs: This helper loads sound buffers