Speech operated noise attenuation device

Claim 1

A speech operated noise attenuation device for reducing background noise in audio signals input to said speech operated noise attenuation device, said speech operated noise attenuation device receiving only un-processed speech signals from a radio receiver demodulator, said speech operated noise attenuation device comprising: a current controlled attenuator receiving audio signals, having a control input, that varies the attenuation of audio signals input to said current controlled attenuator in response to a control signal input to said current controlled attenuator through said control input; signal processing means, receiving said un-processed audio signals, for dynamically identifying a level of background noise in said un-processed audio signals and for providing a first dynamically varying control signal to said control input of said current controlled attenuator to adjust attenuation of said un-processed audio signals according to changes in the level of said background noise, said signal processing means comprised of: a signal valley detector means for detecting the average minimum background noise signal present in said audio signals, said average minimum background noise signals being identified as the background noise signal level floor, said background noise level floor representing the average minimum background noise signal present in said audio signal and for providing a background noise level reference signal representative of the average minimum background noise level in said audio signal; control circuit means responsive to said background noise level reference signal from said signal valley detector means for generating a second control signal, said second control signal being coupled to said control input of said current controlled attenuator to control attenuation of said audio signal by said current controlled attenuator.