Hi,
I've just started using Psychtoolbox and PsychPortAudio. Using the
provided demos, I've been able to piece together a basic
same/different auditory paradigm which works nicely. However, at the
end of each stimulus presented, there is a very audible "pop" as
though the stimulus is being cut off. This pop is not in the audio
file, since I have presented the same stimuli in Presentation with no
artifact (amplitude is ramped at onset and offset).
I've noticed a similar pop/click effect in the
BasicMultiSoundOutputDemo program provided in the Files section of
this Forum.
Does anyone know what might cause this, and how to remove them?
Thanks!
For other info
machine = intel mac pro workstation
os = osx (tiger)
sound = onboard
and here's the code i'm running
%AX_experiment
% Wait for release of all keys on keyboard:
KbReleaseWait;
% Running on PTB-3? Abort otherwise.
AssertOpenGL;
KbName('UnifyKeyNames');
% Perform basic initialization of the sound driver:
InitializePsychSound(1);
% Open the default audio device [], with default mode [] (==Only
playback),
% and a required latencyclass of zero 0 == no low-latency mode, as well as
% a frequency of freq and nrchannels sound channels.
% This returns a handle to the audio device:
freq = 16000;
nrchannels = 1;
pahandle1 = PsychPortAudio('Open', [], [], 3, freq, nrchannels);
pahandle2 = PsychPortAudio('Open', [], [], 3, freq, nrchannels);
filename1 = 'mline2_38.wav';
filename2 = 'mline2_38.wav';
%startSecs = GetSecs;
%timeSecs = KbWait;
%[ keyIsDown, t, keyCode ] = KbCheck;
%fprintf('"%s" typed at time %.3f seconds\n', KbName(keyCode),
timeSecs - startSecs);
AX_trial(pahandle1,filename1,pahandle2,filename2,0.55);
PsychPortAudio('Close');
function AX_trial(pahandle1, wavfilename1, pahandle2, wavfilename2, ISI)
% Read WAV file from filesystem:
wavedata1 = wavread(wavfilename1)';
wavedata2 = wavread(wavfilename2)';
% Fill the audio playback buffer with the audio data 'wavedata':
PsychPortAudio('FillBuffer', pahandle1, wavedata1,0);
PsychPortAudio('FillBuffer', pahandle2, wavedata2,0);
t1 = PsychPortAudio('Start', pahandle1, 1, 0, 1);
PsychPortAudio('Stop',pahandle1,1);
wait = t1+ISI;
t3 = PsychPortAudio('Start', pahandle2, 1, wait, 1);
PsychPortAudio('Stop',pahandle2,1);
I've just started using Psychtoolbox and PsychPortAudio. Using the
provided demos, I've been able to piece together a basic
same/different auditory paradigm which works nicely. However, at the
end of each stimulus presented, there is a very audible "pop" as
though the stimulus is being cut off. This pop is not in the audio
file, since I have presented the same stimuli in Presentation with no
artifact (amplitude is ramped at onset and offset).
I've noticed a similar pop/click effect in the
BasicMultiSoundOutputDemo program provided in the Files section of
this Forum.
Does anyone know what might cause this, and how to remove them?
Thanks!
For other info
machine = intel mac pro workstation
os = osx (tiger)
sound = onboard
and here's the code i'm running
%AX_experiment
% Wait for release of all keys on keyboard:
KbReleaseWait;
% Running on PTB-3? Abort otherwise.
AssertOpenGL;
KbName('UnifyKeyNames');
% Perform basic initialization of the sound driver:
InitializePsychSound(1);
% Open the default audio device [], with default mode [] (==Only
playback),
% and a required latencyclass of zero 0 == no low-latency mode, as well as
% a frequency of freq and nrchannels sound channels.
% This returns a handle to the audio device:
freq = 16000;
nrchannels = 1;
pahandle1 = PsychPortAudio('Open', [], [], 3, freq, nrchannels);
pahandle2 = PsychPortAudio('Open', [], [], 3, freq, nrchannels);
filename1 = 'mline2_38.wav';
filename2 = 'mline2_38.wav';
%startSecs = GetSecs;
%timeSecs = KbWait;
%[ keyIsDown, t, keyCode ] = KbCheck;
%fprintf('"%s" typed at time %.3f seconds\n', KbName(keyCode),
timeSecs - startSecs);
AX_trial(pahandle1,filename1,pahandle2,filename2,0.55);
PsychPortAudio('Close');
function AX_trial(pahandle1, wavfilename1, pahandle2, wavfilename2, ISI)
% Read WAV file from filesystem:
wavedata1 = wavread(wavfilename1)';
wavedata2 = wavread(wavfilename2)';
% Fill the audio playback buffer with the audio data 'wavedata':
PsychPortAudio('FillBuffer', pahandle1, wavedata1,0);
PsychPortAudio('FillBuffer', pahandle2, wavedata2,0);
t1 = PsychPortAudio('Start', pahandle1, 1, 0, 1);
PsychPortAudio('Stop',pahandle1,1);
wait = t1+ISI;
t3 = PsychPortAudio('Start', pahandle2, 1, wait, 1);
PsychPortAudio('Stop',pahandle2,1);