Echo canceler E-side speech detector
AssigneeLucent Technologies Inc.
InventorsDonald Lars Duttweiler, Cheng Kim, Ying Get Tao
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Abstract
The detection of echo is enhanced using a coarse near-end speech detector at a Y-side of an echo canceler and using a more accurate near-end speech detector at the E-side of the echo canceler, such that the latter detector uses a representation of far-end speech and a threshold value to determine if the magnitude of the echo canceler output is larger than that of an echo signal only. If it is, and there is an absence of an indication of the presence of near-end speech from the coarse detector, then the more accurate speech detector adjusts the value of the threshold in a first direction, otherwise it adjusts the threshold in a second direction, to more "finely tone" such accuracy.
Claims14
An echo canceler having an adaptive filter, said echo canceler comprising
- an adder circuit,
- a first near-end speech detector, and
- a second near-end speech detector, said second near-end speech detector comprising,
- means for receiving speech signals via a connection extending to a far-end source of speech signals and for processing said received speech signals to derive a representation of the signal level of the far-end speech,
- means, responsive to said derivation of said signal level, for determining as a function of said representation and a current value of a threshold variable if a signal outputted by the canceler has a magnitude larger than that of an echo signal only, and
- means, responsive to said signal having said larger magnitude and an absence of an indication of a presence of near-end speech from said first near-end speech detector, for decreasing the value of said threshold variable, otherwise increasing the value of said threshold variable.
A speech detector for an echo canceler, said speech detector comprising
- means, connected via a unidirectional communication path to a source of far-end speech signals, for receiving said far-end speech signals and deriving a representation of the far-end speech,
- a first speech detector operative for monitoring another unidirectional path extending to a source of near-end signals and outputting an indication whenever said near-end signals contain near-end speech, and
- a second speech detector for determining as a function of said representation and a current value of an adaptive threshold value, .alpha..sub.E, if an output from said echo canceler has a magnitude larger than that of an echo signal only, said second speech detector further comprising
- means for decreasing the value of said adaptive threshold, .alpha..sub.E, if (a) said indication from said first speech detector is absent and (b) said current near-end signal has said larger magnitude, and increasing the value of said adaptive threshold if condition (a) or (b) is otherwise.
A method of operating an echo canceler, said echo canceler including an adaptive filter, adder circuit and first and second near-end speech detectors, said method comprising the steps of
- receiving speech signals via a connection extending to a far-end source of speech signals and processing the received speech signals to derive a representation of the signal level of the far-end speech,
- at said second near-end detector, responsive to the derivation of said signal level, determining as a function of said representation and a current value of a threshold variable if an output from said echo canceler has a magnitude larger than that of an echo signal only, and
- at said second near-end detector, responsive to said signal having said larger magnitude and an absence of an indication of a presence of near-end speech from said first near-end speech detector, for decreasing the value of the threshold variable, otherwise increasing the value of the threshold variable.
Dependencies are inferred from the claim text.