The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 16, 1996
Filed:
Nov. 19, 1993
Juha Kuusama, Tampere, FI;
Aki Makivirta, Tampere, FI;
Nokia Technology GmbH, Pforzheim, DE;
Abstract
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.