Filter to remove noise from a corrupted song

Hi All,

I need a little help in analyzing this question. I am a student taking
Intro to DSP class and we have this lab in which we're given a corrupted
sound file from which we have to filter out the noise from it.

So, what I did was I plotted out the FFT of the sound file to figure out
where the interference was, and found that the interference is at freq. of
+ and - 44.04 kHz with magnitude of 2.023*10^5. So, now I gotta filter out
this component using the code snippet below:

[b,a] = zp2tf(z, p, k);
filtered_signal = filter(b, a, corrupt_signal);

The problem I have is in analyzing this thing. How would I know the zeros
and poles for the filter with transfer function [b,a]? I know that the
frequency component at 44.04 kHz is causing the problem, and I know that
the sampling frequency of the signal is 44.1 kHz. So, how would I
determine the poles and zeros of the filter's transfer function so that
that component gets filtered out?

I figure that since the peak of the signal's freq. response is at 44.04
kHz, does that mean the pole of the filter would be at 44.04 kHz? And what
about the zeros of the filter? Am I thinking the right way?

Thanks for the help every1, I know this is a very basic question, but a
li'l hint would be great ;)

Farah.


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