Wiener Filter for noise reduction (URGENT HELP REQUIRED)

Hi,

I am doing my project in noise cancellation and i am implementing it using matlab.I have recorded my noisy speech and simultaneously recorded the noise using different recording device.I am making a FIR filter which will remove or reduce the noise.

The theory says that if

x=d+v

d=desired signal
v=noise

Now in order to calculate the coefficients for the filter which will produce a noise v' and when when added to x will remove the noise and leave the desired signal.

To calculate the coeffiecients of the filter

b=Rdx/Rxx

Where Rdx is the cross correlation estimate between d and x and Rxx is auto correlation between x

Problem: (1) How do i cross correlate d and x i know it is xcorr function but how do i obtain only d signal?
(2) How should i use the filter function to implement my coefficients on the noisey signal to get v'?



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That's basically a misunderstanding of the optimum filter concept. In the usual case, when you have uncorrelated noise and an "orthogonal" signal, a filter only can reduce spectral components of noise outside the signal band. Wiener filter theory is a rule to calculate this filter, no matter how big or small it's effect may be. With a speech signal, it probably isn't very effective. Substracting a noise component, as you imagine, would only be possible with a correlated (e. g. periodical noise) or noise correlated to the signal, e. g. nonlinear distortions.