Patent ID: 6963648

Claim:
An echo/noise canceling device for suppressing echoes and background noise during Internet telephony using a personal computer (PC) coupled to the Internet, comprising: left and right loudspeaker inputs means for accepting left and right loudspeaker signals emanating from said PC; left and right loudspeaker output means; signal combining means coupled to said loudspeaker input means for providing combined left and right loudspeaker signal; echo logic circuit means coupled to said signal combining means for generating a microphone attenuator control signal responsive to said loudspeaker signals; left and right channel attenuator means responsive to a speaker attenuation control signal coupled to said speaker input means and providing attenuated left and right loudspeaker signals coupled to respective left and right loudspeaker output means; microphone input signal means; microphone output means for providing an audio signal to said PC; means for providing an audio-mix signal derived from said microphone input signal and coupled to said microphone input means; microphone attenuation circuit means responsive to said microphone attenuator control signal coupled to said audio-mix signal; mute control means responsive to a microphone mute control signal coupled to said audio-mix signal and to said microphone output means; a mute control amplifier coupled to said audio-mix signal having a gain of approximately 39 dB and a band-pass response centered about approximately 4.2 kilohertz with 3 dB cutoff points at approximately 723 hertz and 12.5 kilohertz coupled to a Mute Control Filter having a second order low-pass filter response of approximately 723 hertz with a 3 dB cutoff point at approximately 1.25 kilohertz driving an absolute valve circuit with a gain of approximately 0.5 providing a DC signal driving an integrator amplifier having an RC time charging constant of approximately 29 milliseconds and a discharge time constant of approximately 941 milliseconds and DC gain of approximately 21 dB further driving an R/C Control circuit thus generating said speaker attenuation control signal; and a voltage comparator circuit coupled to said speaker attenuation signal with a trip point of approximately 1.0 volts for generating said microphone mute control signal.