Does audiowrite have an anti-aliasing filter?

Hi all,

I have created a sinusoid s1 with frequency 1000 Hz as following:

f = 1000;
Fs1 = 44100;
Ts1 = 1/44100;
t1 = 0:Ts1:1;
s1 = sin(2*pi*f*t1);

I can play it and save it as a .wav file as following at it works.

soundsc(s1, Fs1)
audiowrite('Original_1000Hz.wav',s1,Fs1)

Now I want to create an aliased frequency (for education purposes) and do the same, showing that the frequency is different. soundsc plays indeed the aliased frequency, but when I saved it with audiowrite and play it outside Matlab I will just hear silence.

Fs2 = 1500;
Ts2 = 1/Fs2;
t2 = 0:Ts2:1;
s2 = sin(2*pi*f*t2);
soundsc(s2, Fs2)
audiowrite('Aliased_500Hz.wav',s2,Fs2)

Why is that? Does audiowrite have an antialiasing filter or something like that? The interesting fact is that sounsc is correctly emitting sound at the right frequency.

Thanks!

Cecilia

Answer 1

[Jan]

No, audiowrite does not modify the data. Otherwise you would find this detail in the docs. Consider that something else goes wrong, perhaps you are writing to a different folder than you think you do. Or the method " play it outside Matlab" is broken: Perhaps you hit the "mute" button of the software?

[Cecilia]

Thanks for your answer Jan, I am writing in the right folder. The new .wav file is indeed there, but I can just here silence. It should be something related to the sample rate, as the same procedure works with a 44.1 kHz sample rate as I explained in the first part.