anchor: SoundData:getSample
  Gets the value of the sample-point at the specified position. For stereo SoundData objects, the data from the left and right channels are interleaved in that order.
  sample = SoundData:getSample( i )
  i number An integer value specifying the position of the sample (starting at 0).
  sample number The normalized samplepoint (range -1.0 to 1.0).
  sample = SoundData:getSample( i, channel )
  i number An integer value specifying the position of the sample (starting at 0).
  channel number The index of the channel to get within the given sample.
  sample number The normalized samplepoint (range -1.0 to 1.0).