A filter that includes an analyzer, thresholding circuit, and synthesizer.
The analyzer generates a low-frequency component signal and a
high-frequency component signal from an input signal. The thresholding
circuit generates a processed high-frequency signal from the
high-frequency component signal, the processed high-frequency signal
having an amplitude of zero in those regions in which the high-frequency
component signal has an amplitude that is less than a threshold value.
The synthesizer generates a filtered signal from input signals that
include the low-frequency component signal and the processed
high-frequency signal. The filtered signal is identical to the input
signal if the threshold value is zero. The analyzer is preferably
constructed from a plurality of finite impulse response filters that
operate on a small fraction of the input signal at a time.