EEG Triggers with sound

Dear All,

I'm really new to Matlab so, please be patient if this seems like a silly question to most of you. I'm trying to implement just a really simple presentation code. The idea is to present a sound (a "Beep") at random times every 10/15 seconds from the offset of the previous sound. What i would like to implement is a trigger for our EEG system, so that a every time the sound is played the trigger is sent to our EEG (A neuroconn Neuroprax system). Could somebody please help me with this, would be much appreciated. This is what I did so far for the stimuli presentation:

 % Clear the workspace and the screen

 close all;
 clearvars;

 PsychDefaultSetup(2);
 AssertOpenGL;

 Screen('Preference','SkipSyncTests', 1); 

 screens = Screen('Screens');

 screenNumber = max(screens);

 % Define black and white
  white = WhiteIndex(screenNumber);
  black = BlackIndex(screenNumber);

 % Open an on screen window
  [window, windowRect] = PsychImaging('OpenWindow', screenNumber, black);

 % Query the frame duration
  ifi = Screen('GetFlipInterval', window);

 % Set up alpha-blending for smooth (anti-aliased) lines
  Screen('BlendFunction', window, 'GL_SRC_ALPHA', 'GL_ONE_MINUS_SRC_ALPHA');

 % Get the size of the on screen window in pixels
  [screenXpixels, screenYpixels] = Screen('WindowSize', window);

[xCenter, yCenter] = RectCenter(windowRect);

Screen('TextFont', window, 'Ariel');
Screen('TextSize', window, 36);

line1 = 'Hello and Thanks for your participation';
line2 = '\n\n\n\n In this experiment you''ll see a fixation cross and 
         you''ll hear a "BEEP" sound at different time intervals';
line3 = '\n\n You can freely choose when you want to perform the movement 
         AFTER the "BEEP"';
line4=  '\n\n\n\n\n\n When you are ready .... lets start';

 % Draw all the text in one go
  Screen('TextSize', window, 20);
  DrawFormattedText(window, [line1 line2 line3 line4],...
    'center', screenYpixels * 0.25, white);

 % Flip to the screen
  Screen('Flip', window);

KbStrokeWait;

 %----------------------------------------------------------------------

 % Here we set the size of the arms of our fixation cross
  fixCrossDimPix = 40;

 % set the coordinates 
  xCoords = [-fixCrossDimPix fixCrossDimPix 0 0];
  yCoords = [0 0 -fixCrossDimPix fixCrossDimPix];
  allCoords = [xCoords; yCoords];

 % Set the line width for our fixation cross
  lineWidthPix = 4;

 % Draw the fixation cross 
  Screen('DrawLines', window, allCoords,...
    lineWidthPix, white, [xCenter yCenter], 2);

 % Flip to the screen
  Screen('Flip', window);

 %-----------------------------------------------------------------------

 % Initialize Sounddriver
  InitializePsychSound(1);

 % Number of channels and Frequency of the sound
  nrchannels = 2;
  freq = 48000;

 % How many times to we wish to play the sound
  repetitions = 1;

 % Length of the beep
  beepLengthSecs = 0.2 ;

 % Length of the pause between beeps
  beepPauseTime =  WaitSecs(randi([1, 5]));

 % Start immediately (0 = immediately)
  startCue = WaitSecs(5);

waitForDeviceStart = 1 ;

pahandle = PsychPortAudio('Open', [], 1, 1, freq, nrchannels);

 % Set the volume to half for this demo
  PsychPortAudio('Volume', pahandle, 0.5);

 % Make a beep which we will play back to the user
  myBeep = MakeBeep(500, beepLengthSecs, freq);

 % Fill the audio playback buffer with the audio data, doubled for stereo
 % presentation
  PsychPortAudio('FillBuffer', pahandle, [myBeep; myBeep]);

 % Start audio playback 1
  PsychPortAudio('Start', pahandle, repetitions, startCue, 
  waitForDeviceStart);
  WaitSecs(randi([10, 15])); 

 % Start audio playback 2
  PsychPortAudio('Start', pahandle, repetitions, startCue, 
  waitForDeviceStart);
  WaitSecs(randi([10, 15])); 

 % Start audio playback 3
  PsychPortAudio('Start', pahandle, repetitions, startCue, 
  waitForDeviceStart);
  WaitSecs(randi([10, 15])); 

 % Start audio playback 4
  PsychPortAudio('Start', pahandle, repetitions, startCue, 
  waitForDeviceStart);
  WaitSecs(randi([10, 15])); 

 % Close the audio device
  PsychPortAudio('Close', pahandle); 
 % Clear the screen
 sca;

Thanks and bests.

Answer 1

[pierre emmanuel lemesre]

Dear Den,

did you find a solution to your problem?

I try, me too, to send a trigger to my NIRS recorder in response at an audio stimulus.

If you find the solution, can you reply me.It will be helpfull.

Thanks and bests