US 5,636,323 A · Speech communication apparatus having an echo canceler

Abstract

The invention is directed to an apparatus for speech communication that includes an echo canceler (3) for canceling an acoustic echo component input from a hands-free speech loudspeaker (13) to a microphone (14). The echo canceler (30) is provided with a volume control (36) for variably controlling the volume of a received speech signal, an amplitude limiter (35) for limiting the amplitude of an output signal from the volume control (36), an echo canceler (32, 32) for estimating a pseudo echo signal from an output from the amplitude limiter and subtracting the estimated pseudo echo signal from the transmitted speech signal input from the microphone (14), and a nonlinear filter (34) for processing an output from the echo canceler, thereby limiting the amplitude level of the received speech signal to a predetermined level or less. Accordingly, even if a received speech signal having a high received speech signal level is input to the echo canceler, the received speech is not distorted, and an acoustic echo can be sufficiently canceled by the echo canceler.

Claims14

Dependent claims

A speech communication apparatus, comprising:

transceiver means for transmitting and receiving a speech signal;
loudspeaker means for outputting a speech signal received by said transceiver means;
microphone means for inputting a speech signal to be transmitted;
means, connected between said loudspeaker means and said transceiver means and between said microphone means and said transceiver means, for canceling an acoustic echo generated upon inputting the received speech signal output from said loudspeaker means to said microphone means;
means for limiting, to a predetermined value, an amplitude of the received speech signal to
means for limiting, to a predetermined value, an amplitude of the received speech signal to be input to said echo canceling means, when said amplitude exceeds the predetermined value;
means, connected to an output of said amplitude limiting means, for decreasing/increasing an amplitude of the received speech signal output from said amplitude limiting means:
and
means for decreasing/increasing the predetermined limit value in association with an increase/decrease of the amplitude of the received speech signal by said amplitude decreasing/increasing means.

6 more elements

Dependencies are inferred from the claim text.

Speech communication apparatus having an echo canceler

Life of this patent

Speech communication apparatus having an echo canceler

Life of this patent

Abstract

Claims14