A multi-band signal processor for digital audio signals

摘要

The present invention relates to a multi-band signal processor comprising a signal input for receipt of a digital audio input signal and a cascade of digital all-pass filters configured for receipt of the digital audio input signal and generation of M delayed digital audio signal samples at respective tapping nodes interposed between the digital all-pass filters. The multi-band signal processor comprises a signal convolution processor configured for convolving the M delayed digital audio signal samples with M time-varying filter coefficients of a processing filter to produce a processed digital output signal. A frequency domain transform processor is configured for converting the M delayed digital audio signal samples to frequency domain representation to produce respective signal spectrum values in a predetermined number of frequency bands, N. A level estimator is configured to compute respective signal level estimates in the predetermined number of frequency bands based on the respective signal spectrum values. A processing gain calculator of the multi-band signal processor is configured for computation of a frequency domain gain coefficient for each of the predetermined number of frequency bands based on the respective signal level estimates and band gain laws. An inverse frequency domain transform processor is configured for conversion of the N frequency domain gain coefficients into the M time-varying filter coefficients of the processing filter. The frequency domain transform processor is configured to compute signal spectrum values of at least two different frequency bands at different band update rates. Each of M and N is a positive integer number.