BasicMultiSoundOutputDemo([repetitions=0][, wavfilename])
Play a background "sound track", and then in intervals of 1 seconds a
short 0.1 secs beep of varying pitch. The first beep starts 5 seconds
after onset of the background sound track, the sound track loops forever.
Stop the demo by pressing any key for at least 1 second.
repetitions = Number of repetitions of the sound. Zero = Repeat forever
(until stopped by keypress), 1 = Play once, 2 = Play twice, ....
wavfilename = Name of a .wav sound file to load and playback. Otherwise
the good ol' handel.mat file (part of Matlab) is used.
Psychtoolbox/PsychDemos/BasicMultiSoundOutputDemo.m