US 5,327,496 A · Communication device, apparatus, and method utilizing pseudonoise signal for acoustical echo cancellation

Abstract

A communication device, an apparatus, and a method for acoustic echo cancellation which makes use of a pseudonoise signal. An audio mixer adds the pseudonoise signal to an input signal received from another communication device to produce a first composite signal. An audio system converts the first composite signal to sound in an at least partially enclosed space. The at least partially enclosed space produces an acoustical echo in response. The audio system then converts the acoustical echo and other sounds in the at least partially enclosed space to a second composite signal. A signal processor cross-correlates the second composite signal with the pseudonoise signal to produce an estimate of the overall impulse response of the combined system formed by the at least partially enclosed space and the audio system. The processor then convolves the first composite signal with the impulse response estimate to produce an echo estimation signal. The echo estimation signal is an estimate of the component of the second composite signal which corresponds to the acoustical echo. The processor then subtracts the echo estimation signal from the second composite signal to produce an output signal.

Claims24

Dependent claims

A communication device comprising:

a signal generator for generating a pseudonoise signal;
an audio mixer responsive to an input audio signal and said pseudonoise signal for combining said input audio signal with said pseudonoise signal to produce a first composite signal;
an audio system responsive to said first composite signal for converting said first composite signal to sound in an at least partially enclosed space, said at least partially enclosed space producing an acoustical echo in response, said audio system also for converting said acoustical echo and other sounds in said at least partially enclosed space to a second composite signal, said second composite signal including an echo component corresponding to said acoustical echo, said at least partially enclosed space and said audio system together forming a combined system having an overall impulse response;
means responsive to said second composite signal and said pseudonoise signal for generating a first estimate of said overall impulse response;
means responsive to said first composite signal and said first estimate for generating an echo estimation signal corresponding to an estimate of said echo component of said second composite signal;
and
means for subtracting said echo estimation signal from said second composite signal to produce an output audio signal.

4 more elements

An acoustical echo cancellation apparatus for use with an audio system, said audio system responsive to a first composite signal for converting said first composite signal to sound in an at least partially enclosed space, said at least partially enclosed space producing an acoustical echo in response, said audio system also for converting said acoustical echo and other sounds in said at least partially enclosed space to a second composite signal, said second composite signal including an echo component corresponding to said acoustical echo, said at least partially enclosed space and said audio system together forming a combined system having an overall impulse response, said apparatus comprising:

a signal generator for generating a pseudonoise signal;
an audio mixer responsive to an input audio signal and said psneudonoise signal for combining said input audio signal with said pseudonoise signal to produce said first composite signal;
means responsive to said second composite signal and said pseudonoise signal for generating a first estimate of said overall impulse response;
means responsive to said first composite signal and said first estimate for generating an echo estimation signal corresponding to an estimate of said echo component of said second composite signal;
and
means for subtracting said echo estimation signal from said second composite signal to produce said output audio signal.

3 more elements

A method of acoustical echo cancellation for use with an audio system, said audio system responsive to a first composite signal for converting said first composite signal to sound in an at least partially enclosed space, said at least partially enclosed space producing an acoustical echo in response, said audio system also for converting said acoustical echo and other sounds in said at least partially enclosed space to a second composite signal, said second composite signal including an echo component corresponding to said acoustical echo, said at least partially enclosed space and said audio system together forming a combined system having an overall characteristic impulse response, said method comprising the steps of:

generating a pseudonoise signal;
combining an input audio signal with said pseudonoise signal to form said first composite signal;
generating a first estimate of said overall impulse response in response to said second composite signal and said pseudonoise signal;
generating an echo estimation signal corresponding to an estimate of said echo component in response to said first composite signal and said first estimate;
and
subtracting said echo estimation signal from said second composite signal to produce an output signal.

3 more elements

Dependencies are inferred from the claim text.

Communication device, apparatus, and method utilizing pseudonoise signal for acoustical echo cancellation

Life of this patent

Communication device, apparatus, and method utilizing pseudonoise signal for acoustical echo cancellation

Life of this patent

Abstract

Claims24