Function mixSynth

Additively mix a signal from specified synthesizer to a given portion of a sound. sound = a sound object to write to channel = channel to fill (beginning from 0) synth = synthesizer object freq = synthesizer frequency startTime = start time of a signal in seconds duration = duration of a signal in seconds amplitude = volume coefficient of a signal

void mixSynth (
  Sound sound,
  uint channel,
  Synth synth,
  float freq,
  double startTime,
  double duration,
  float amplitude