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How to randomize audio files

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Takara Sumoto
Takara Sumoto on 10 Sep 2019
Commented: Takara Sumoto on 11 Sep 2019
I have 80 audio files and want to play them randomely (not in the file number's orders).
My code so far is;
for i=1:length(audio_files)
aud_file=strcat('C:\toolbox\aud_file\',audio_files(i).name);
% load sound file (make sure that it is in the same folder as this script)
[soundData freq]=audioread(aud_file);
% opens sound buffer at a different frequency
pahandle = PsychPortAudio('Open', [], [], 2, []);
% loads data into buffer
PsychPortAudio('FillBuffer', pahandle, soundData');
% how many repititions of the sound
repetitions=1;
%starts sound immediatley
PsychPortAudio('Start', pahandle, repetitions,0);
% stop
PsychPortAudio('Stop', pahandle, 1,0);
%wait
WaitSecs(1);
%close
PsychPortAudio('Close', pahandle);
end
I searched the code to rondomize which is;
a=zeros(1,80);
for i=1:80
a=randperm(80);
end
But I'm not sure where I should add this randomize code.
Should the code be somewhere in the audio loop or before the loop?

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Accepted Answer

David K.
David K. on 10 Sep 2019
It looks to me that the line
aud_file=strcat('C:\toolbox\aud_file\',audio_files(i).name);
is where you get a song. Since the loop variable i is how you are currently getting the songs you can instead use it to index your random sequence. So, you can put it before the loop and index it to get the random values you want.
a=randperm(80);
for i=1:length(audio_files)
aud_file=strcat('C:\toolbox\aud_file\',audio_files(a(i)).name);
I removed everything else from the randomizer code you posted since I am pretty sure it is unneccessary.

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Show 2 older comments
Takara Sumoto
Takara Sumoto on 10 Sep 2019
Yes, they are playing just in the order.
Walter Roberson
Walter Roberson on 10 Sep 2019
Are you sure you used
aud_file=strcat('C:\toolbox\aud_file\',audio_files(a(i)).name);
and not
aud_file=strcat('C:\toolbox\aud_file\',audio_files(i).name);
Takara Sumoto
Takara Sumoto on 11 Sep 2019
That's what I was doing wrong!
It works now.
Thank you very much for your help!

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More Answers (1)

Johannes Fischer
Johannes Fischer on 10 Sep 2019
Edited: Johannes Fischer on 10 Sep 2019
What kind of randomization do you want?
Play all sounds once, before playing a sound twice?
randomizedOrder = randperm(80);
for i = randomizedOrder
% ...load and play audio
end
Or every time you load a file, each sound has the same probability of being loaded.
% number of consecutive audio playbacks
N = 10;
randomizedOrder = ceil(rand(1, N)*80);
for i = randomizedOrder
% ...load and play audio
end

  1 Comment

Takara Sumoto
Takara Sumoto on 10 Sep 2019
Thank you for the repley.
In the experiment, I'm going to play 80 audio files in a row (including "wait", "beep cue", "key press", etc. for each file), but I want to randomize files for each perticipant.
I tried both codes above but I coud only play in the order.

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