>Psychtoolbox>PsychTests

AudioFeedbackLatencyTest([trigger=0.1] [, nrtrials=10] [, freq=44100][, freqout=44100][, runmode=1])

Tries to test sound onset accuracy of PsychPortAudio without need for
external measurement equipment: Sound signals are played back via
PsychPortAudio at well defined points in time, using low-latency mode. At
the same time, sound is captured via PsychPortAudio’s capture facilities.
The idea is that the microphone or line-in connector should pick up and
capture the sound signals emitted through line-out (via a line-out ->
line-in feedback cable) or emitted through the speakers. We measure and
compare timing of emitted vs. captured sound spikes.

Results on MacbookPro suggest that the method works, but with a not 100%
accuracy, so its still better to use external measurement equipment to
test!!!

EARLY BETA CODE: DON’T USE OR USE WITH GREAT CAUTION!

Optional parameters:
‘trigger’ = Trigger level for detection of sound onset in captured sound.

‘ntrials’ = Number of measurement trials to perform.

‘freq’ = Samplerate of capture device.

‘freqout’ = Samplerate of playback device.

Obviously this test function can only be used in a very silent room!