Returns Datapixx Audio OUT group delay in seconds.
This is the time between when a schedule sends a data sample to the CODEC, and
when that sample has greatest output at the “Audio OUT” jack of the Datapixx.
Due to the way in which CODECs operate, this delay is a function of the sample
rate. For greatest precision in audio stimulus timing, this value could be
subtracted from the scheduleOnset parameter before calling SetAudioSchedule.
See DatapixxAudioFeedbackDemo for an example.