Juha Kuusama

System for processing an audio signal so as to reduce the noise contained therein by monitoring the audio signal content within a plurality of frequency bands

The invention relates to a system for processing an audio signal to reduce the noise contained therein, the system comprising a source (1) of an audio signal in electric form, a first filter group (2) for dividing the audio signal into several subband signals in different frequency bands, a detector (3) for each subband signal to detect the audio signal level thereof, and a compressor/expander (4) for compressing/expanding each subband signal on the basis of the detected audio signal level thereof, and a second filter group (5) for combining the compressed/expanded subband signals to generate a reconstructed audio signal (6). According to the invention the first filter group (2,5) is arranged to divide the sound frequency range into bands with a width enabling the processing of the signal within the critical bands, and each compressor/expander (4) is arranged to attenuate the signal in its band when the detector (3) associated therewith has detected that the audio signal is missing from said frequency band.