US 5,633,936 A · Method and apparatus for detecting a near-end speech signal

Abstract

An acoustic echo canceler (10) includes an adaptive filter circuit (12) and a near-end speech detection circuit (14). The adaptive filter circuit (12) includes an adaptive filter that may be of a single or dual filter structure for generating an e(t) acoustic echo canceler output signal (26) in response to an s(t) far-end speech signal (20) and an x(t) send-in signal (28). The near-end detection circuit (14) receives the s(t) far-end speech signal (20) and the x(t) send-in signal (28) at a high pass filter (32) and a high pass filter (36), respectively. The filtered s(t) far-end speech signal (20) and the filtered x(t) send-in signal (28) are averaged over a selected sampling period by a far-end sampling circuit (34) and a send-in sampling circuit (38). A divider circuit (40) generates a .gamma.(t) acoustic echo path gain/loss signal (42) in response to the filtered and averaged s(t) far-end speech signal (20) and x(t) send-in signal (28). A near-end detector (44) compares the .gamma.(t) acoustic echo path gain/loss signal (42) with a .rho..sub..gamma. long term average signal (46) generated from the .gamma.(t) acoustic echo path gain/loss signal (42) to determine a first condition for near-end speech detection. Near-end detector (44) also compares an e(t) average power signal (51) of the e(t) acoustic echo canceler output signal (26) as generated by a power sampling circuit (50) with its .rho..sub.e long term average signal (53) generated by a long term echo canceler averaging circuit (52) as a second condition.

Claims18

Dependent claims

A method of detecting a near-end speech, comprising the steps of:

determining an average power of an acoustic echo canceler output signal over a selected sampling period in response to a received send-in signal from a microphone and an adaptive filter output signal of an adaptive filter;
filtering a far-end speech signal, the far-end speech signal generating the adaptive filter output signal;
filtering the received send-in signal;
determining an average of the filtered far-end speech signal over the selected sampling period;
determining an average of the filtered received send-in signal over the selected sampling period;
determining an acoustic echo path gain/loss, the acoustic echo path gain/loss being a ratio of the averaged filtered received send-in signal and the averaged filtered far-end speech signal;
determining a long-term power average of the acoustic echo canceler output signal;
determining a long term average of the acoustic echo path gain/loss;
comparing the acoustic echo path gain/loss with the long term average of the acoustic echo path gain/loss;
and
comparing the average power of the acoustic echo canceler output signal with the long term power average of the acoustic echo canceler output signal in order to detect a presence of the near-end speech signal.

8 more elements

A near-end speech detection device for use in an acoustic echo canceler, comprising:

a first high pass filter operable to receive a far-end speech signal, said first high pass filter operable to remove low frequency components of said far-end speech signal;
a far-end sampling circuit operable to generate an average signal of said far-end speech signal over a selected sampling period;
a second high pass filter operable to receive a send-in signal, said send-in signal including a far-end speech component, a near-end speech component, and a noise component, said second high pass filter operable to remove low frequency components of said send-in signal;
a send-in sampling circuit operable to generate an average signal of said send-in signal over said selected sampling period;
a divider circuit operable to generate an acoustic echo path gain/loss signal, said acoustic echo path gain/loss signal being a ratio of said average signal of said send-in signal to said average signal of said far-end speech signal;
a long term echo path averaging circuit operable to generate a long term average signal of said acoustic echo path gain/loss signal;
a near-end detector operable to determine a first condition for a presence of near-end speech when said acoustic echo path gain/loss signal is greater than said long term average signal.

4 more elements

Dependencies are inferred from the claim text.

Method and apparatus for detecting a near-end speech signal

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Method and apparatus for detecting a near-end speech signal

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Abstract

Claims18