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Re: address@hidden

From: Przemek Klosowski
Subject: Re: address@hidden
Date: Tue, 14 Sep 2004 09:11:33 -0400 (EDT)

   for some help if some of you can give me a source code in octave that 
   does the following tasks.

   1.) first the program would load a wav file.

   2.) if i'm not mistaken, the wav file is in time-domain format. it 
   needs FFT (fast fourier transform) for it to be in the frequency domain.

   3.) it then passes through a notch filter which filters out the 
   noise. the noise is the hissing sound you hear when you play cassette tapes 
   or old records. the output is then converted back to a wav file.

   This project is actually for an audio filter for old records. first 
   we need to figure out the frequency of the "hissing" sound so that we 
   can remove it using the notch filter.

I think you are in for more than you bargained for. The hissing that
you refer to is not a single frequency that would be taken out by a
notch filter--rather, it's a pink, broadband noise that you'd need a
low-pass filter for. Such filter probably should be adaptive. SoX
actually has some pop/click/noise removal tools.

You can read about some techniques used for removing audio flaws
from analog recordings in

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