Noise reduction circuit for telephones
AssigneeAcoustic Technologies, Inc.
InventorSAMUEL L. THOMASSON
Life of this patent
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Abstract
A system for processing audio signals in two channels, wherein each channel includes a plurality of band pass filters for dividing the signal in each channel into a plurality of bands and a plurality of variable gain amplifiers coupled one each to a band pass filter. Control logic coupled to the variable gain amplifiers prevents the signals in adjacent bands within a channel from being attenuated simultaneously. The control logic attenuates the signals in one channel in accordance with the signal in the corresponding bands in the other channel. In some circumstances, the signal in the band in the one channel is attenuated.
Claims8
A method for processing audio signals, said method comprising the steps of:
- dividing the signals into two channels;
- dividing each channel into a plurality of bands;
- monitoring the amplitude of the signal in each band;
- and,
- for each band having a signal above a predetermined threshold, attenuating the signal in the corresponding band in the other channel, except that the signals in adjacent bands in a channel may not be fully attenuated.
In a noise reducing circuit for processing audio signals in two channels, wherein each channel includes a plurality of band pass filters for dividing the signal in each channel into a plurality of bands, the improvement comprising:
- a plurality of variable gain amplifiers coupled one each to a band pass filter;
- control logic coupled to the variable gain amplifiers for preventing the signals in adjacent bands within a channel from being attenuated simultaneously.
A noise reducing circuit for processing audio signals comprising:
- a plurality of band pass filters for dividing the signals into a plurality of bands;
- a plurality of detectors coupled one each to a band pass filter, each detector sensing the presence of background noise within a particular band;
- a plurality of variable gain amplifiers, each amplifier having an input coupled to a band pass filter, a control input, and an output;
- a summation circuit coupled to the outputs of the variable gain amplifiers;
- control logic coupled to said detectors and to the control inputs of the variable gain amplifiers for preventing the signals in adjacent bands within a channel from being attenuated simultaneously.
Dependencies are inferred from the claim text.