How to randomize audio files

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?

Answer 1

[David K.]

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.

[Takara Sumoto]

Thank you very much.

In a theory, it should work but for some reasons it doesn't.

[David K.]

Doesn't work as in the songs are still not playing randomly?

[Takara Sumoto]

Yes, they are playing just in the order.

[Walter Roberson]

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]

That's what I was doing wrong!

It works now.

Thank you very much for your help!

Answer 2

[Johannes Fischer]

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

[Takara Sumoto]

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.