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It is still possible to do better. In the Split Band De-essing all signals above 6 kHz are reduced in gain if sibilants are detecting. The design below is even more precise. A bandpass filter around 8 kHz detects sibilants.Could not load image
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The output of the bandpass filter drives a limiter core and this in turn reduces the gain of a controllable second order peak filter. This limits the gain reduction to the range of frequencies from 6 to 10 kHz. The entire system is shown below:
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