audio compression (shorten an audio file)

I want to compress an audio file to make it shorter to put in a game for sound effects. I use the following:

[y,Fs]=wavread('blast.wav');
t1=0;% start time
t2=2;% end time
yNew=y((Fs*t1+1):Fs*t2,1);
wavwrite(yNew,Fs,'soundShort.wav');

The compression is fine and 'soundShort.wav' can play. But command sound(wavread('soundShort.wav')) no longer has any sound, though it's runnable. I wonder what goes wrong.

[Geoff Hayes]

a - are you really calling the code as

sound('soundShort.wav') 

and so are passing a string to the sound method? If I try that (in my version of MATLAB) then I observe a

Error using sound (line 33)
Audio data must be real and floating point.

What happens when you call

sound(yNew, Fs);

instead? Presumably the yNew array has Fs samples...

[a a]

Sorry I didn't mean to write sound('soundShort.wav'), rather I used sound(wavread('soundShort.wav')). There's no sound nor error message, but the file itself is playable through a media tool and sounds normal.

[Walter Roberson]

sound() with only one input assumes 8000 Hz.

[a a]

Walter Roberson

8000 Hz means?

[Walter Roberson]

8000 samples per second. Fs = 8000 .

[a a]

so what's wrong? how to resolve the problem of no sound running sound(wavread('soundShort.wav'))?

[Walter Roberson]

your original code uses a statement that reads in both the signal and the sampling frequency. You need to do that . Then you need to pass the signal and the sampling frequency to sound() like Geoff posted .

[a a]

no, even after i use

[y,Fs]=wavread('soundShort.wav');sound(y,Fs)

there's no sound.

[Walter Roberson]

What shows up for size(y) and for min(y) and max(y) ?

[a a]

size(y)=81162*2

min(y)=-0.78

max(y)=0.85

[a a]

ok. after further testing, actually sound(y,Fs) has a sound on win10 but doesn't on winXP. what's wrong with winXP on this point?

[Walter Roberson]

http://pcauthorities.com/windows-xp/how-to-troubleshoot-sound-problems-in-windows-xp/

[a a]

thank you. after reading it, i still don't know what went wrong for my winxp. on my winxp, 'beep' has a sound while 'sound(beep)' doesn't.