AUDIO NOISE REDUCTION SYSTEM IMPLEMENTED THROUGH DIGITAL SIGNAL PROCESSING

摘要

A decoder capable of decoding audio signals encoded using analog noise reduction techniques, particularly Dolby A, is implemented by means of digital signal processing. The encoded signal passes through one or more digital filters, producing the decoded signal. The decoded signal is fed back to drive control blocks, which determine the parameters of the digital filters. The determination of these parameters may be arranged so as to emulate closely a given analog noise reduction decoder, such as a Dolby A decoder. The one or more digital filters are relocated to the feed-forward portion of the decoder they are located in the feedback portion of the encoder when performed using analog techniques - to overcome the problems caused by delay introduced by the digital implementation which prevent a direct conversion of the analog decoder to a digital one.