Multi-band signal processor for digital audio signals

A method includes: processing the digital audio input signal to generate M delayed digital audio signal samples; converting the delayed digital audio signal samples to frequency domain representation in N number of frequency bands to compute respective signal spectrum values; determining respective signal level estimates; computing respective frequency domain gain coefficients based on the respective signal level estimates and band gain laws; transforming the frequency domain gain coefficients to time domain representation to produce M time-varying filter coefficients of a processing filter; convolving the M delayed digital audio signal samples with the time-varying filter coefficients to produce the processed digital output signal; and updating the delayed digital audio signal samples in accordance with a sample-by-sample or a predetermined block rate; wherein two of the signal spectrum values for at least two of the frequency bands are updated at different rates; and wherein M and N are positive integer numbers.