var audioBufferSlice = require('audiobuffer-slice');

// audioBuffer slice from 10s to 15s; a 5 second (5000ms) slice.
audioBufferSlice(audioBuffer, 10000, 15000, function(error, slicedAudioBuffer) {
  if (error) {
    console.error(error);
  } else {
    source.buffer = slicedAudioBuffer;
  }
});