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Re: Audio signal

From: Doug Stewart
Subject: Re: Audio signal
Date: Sat, 17 Nov 2007 13:55:10 -0500
User-agent: Thunderbird (Windows/20070809)

polmc wrote:
Ok, I have to synthetize an audio signal. I must do this by suming up the
harmonics of the sound.

So long I've got this:

function sinte(f)
  Fs = 44100;
  tau6 = 0.018;
  A6 = 25.1;
  f6 = f*7;
  x6 = A6*exp(-t/tau6).*sin(2*pi*f6*t/Fs);
tau7 = 0.016;
  A7 = 15.8;
  f7 = f*8;
  x7 = A7*exp(-t/tau7).*sin(2*pi*f7*t/Fs);
tau8 = 0.017;
  A8 = 19.9;
  f8 = f*9;
  x8 = A8*exp(-t/tau8).*sin(2*pi*f8*t/Fs);
tau9 = 0.038;
  A9 = 12.5;
  f9 = f*10;
  x9 = A9*exp(-t/tau9).*sin(2*pi*f9*t/Fs);
tau10 = 0.017;
  A10 = 10;
  f10 = f*11;
  x10 = A10*exp(-t/tau10).*sin(2*pi*f10*t/Fs);
x = x6 + x7 + x8 + x9 + x9 + x10;


When I play the sound, I just hear a short 'puff'.
The thing is that if I take away the '/Fs', It then sounds like a normal
'beep', which is what I want (I guess). Does anyone know what exactly does
the Fs mean?

Yes Fs is the sample frequency. Thus for your code you are sampling the audio signal 44100 samples per second. if you want to hear 5 second of sound then you must get 44100*5 samples anf write it out to the wave file.
You are only generating  854 samples thus only 854/44100 of a second!!!!!


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