How can I make sound randomly occur during 10 second presentation of other stimulus?

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Chelsea 2014-12-4

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评论： Chelsea 2014-12-4

Hi there,

I'm using Psychtoolbox to create an experiment. I have the code for sound, presentation of images, etc. I'm trying to figure out how I might be able to make a 1s sound occur randomly at some point during the 10s presentation of an image?

I don't necessarily need code involving sound, or even Psychtoolbox specific. I'm just wondering if anyone has any suggestions about how to time one stimulus to occur in relation to another.

Thanks!

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Answer 1

William Frane 2014-12-4

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https://ww2.mathworks.cn/matlabcentral/answers/165445-how-can-i-make-sound-randomly-occur-during-10-second-presentation-of-other-stimulus#answer_161276

在 MATLAB Online 中打开

Here's one way of generating a random time:

% Seed the random number generator (otherwise the same random sequence is generated every time)
rng('shuffle'); % Newer versions of MATLAB
%rand('twister', sum(100*clock)); % Older versions of MATLAB
imageTime = 0;
imageDuration = 10;
soundDuration = 1;
% This assumes that you want the sound to be played early enough to ensure that
% its playback has finished by the time the time the image disappears
soundTime = imageTime + rand()*(imageDuration - soundDuration);

See this page for info about seeding the RNG in different versions of MATLAB.

Assuming you have some sort of clock available, you could then use these values like this:

% Initialization code
soundHasPlayed = false;
% Experiment loop
currentTime = ReasonablyAccurateClock();
if (currentTime >= imageTime && currentTime <= (imageTime + imageDuration))
  drawImage();
end
if (currentTime >= soundTime && ~soundHasPlayed)
  playSound();
  soundHasPlayed = true;
end