PsychPort

1

So I would like to play a sound during experimentatation.


The code snippet so far:


-------------------------------------------------

InitializePsychSound(1); 

pahandle = PsychPortAudio('Open', [], [], 3, Fsc, nrchannels, [], [], [], []); %'4' and '16' for max speed

PsychPortAudio('Fillbuffer', pahandle, probetone);

PsychPortAudio('Start', pahandle, 1, 0, 1); 

--------------------------------------------------


Now for timing purposes I wish to add a GetSecs command right after the playback has finished. However, in the current script, the tone is still playing while the Matlab script is running along.


So the regular Matlab function 


-----------------------------------------

playblocking(probe);

-----------------------------------------


...blocks further activity until playback is finished. is there an alternative in PTB-3 for this function?


2



---In PSYCHTOOLBOX@yahoogroups.com, <hcstronks.jhmi.edu@...> wrote :

So I would like to play a sound during experimentatation.


The code snippet so far:


-------------------------------------------------

InitializePsychSound(1); 

pahandle = PsychPortAudio('Open', [], [], 3, Fsc, nrchannels, [], [], [], []); %'4' and '16' for max speed

PsychPortAudio('Fillbuffer', pahandle, probetone);

PsychPortAudio('Start', pahandle, 1, 0, 1); 

--------------------------------------------------


Now for timing purposes I wish to add a GetSecs command right after the playback has finished. However, in the current script, the tone is still playing while the Matlab script is running along.


So the regular Matlab function 


-----------------------------------------

playblocking(probe);

-----------------------------------------


...blocks further activity until playback is finished. is there an alternative in PTB-3 for this function?


-> Look at PsychPortAudio('Stop',...), and use its returned timestamps. Your GetSecs wouldn't be reliable/accurate, neither would be use of playblocking(). Also we have multiple demos about precise timing etc. and info in the ECVP slide decks in the PsychDocumentation/ folder.


-mario


3
Dear Mario,

That was a great help thanks.

A last question - using the standard Matlab function I would do the following:

player = audioplayer(signal, Fs, 16, audioDevID) 
 
The '16' there would be the bits/sample. Is this an important parameter in PTB-3's PsychPortaudio? I couldn't find any reference on it. It seems to work without, but I'm in an audiology setting, so I'd rather be sure of this.

Thanks so much,
Chris
4
Hi Mario,

Thanks for you ongoing support.

Would it be advisable to use a higher end external USB sound card then, given that we are using a laptop for experimentation?

That would add the USB polling time, but would probably result in better behavior.

Thanks heaps,
Chris