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Entry  Mon Nov 5 20:37:01 2012, Ayaka, Update, WienerFiltering, Play with wiener filtering estimate.pngWfilter_notch.png
    Reply  Thu Nov 8 10:11:58 2012, Ayaka, Update, WienerFiltering, Play with wiener filtering document.pdfestimate.pngR_model.png
Message ID: 7688     Entry time: Thu Nov 8 10:11:58 2012     In reply to: 7672
Author: Ayaka 
Type: Update 
Category: WienerFiltering 
Subject: Play with wiener filtering 

I will attach a document which describes how the noise affect the wiener filter and the noise cancellation ratio.

And I re-estimate the SN ratio in the microphone (but still rough):

R_model.png

The yellow line is modeled signal level, and cyan line is modeled noise level.

Then, the estimated filtered residual noise is:

estimate.png

The noise is already subtracted enough below 80 Hz even though there is still coherence.
Above 300 Hz, the residual error is limited by other noise than acoustic noise since there is no coherence.
I am not sure about the region between 100-300 Hz, but I guess that we cannot subtract the acoustic noise because primary noise (see the document), such as a peak at 180 Hz, is so high.

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