Reference microphone for non-linear and time variant echo cancellation
First Claim
1. A method, comprising:
- receiving a far end signal from a far end user and broadcasting the far end signal at a loudspeaker;
determining a signal for use in estimating an echo transfer function, the signal selected from between;
the far end signal and an echo reference signal received from a near field microphone disposed in close proximity to the speaker, the determining the signal based at least in part on a comparison between the far end signal and the echo reference signal, the near field microphone sensing the far end signal that is broadcast from the speaker;
determining an echo transfer function based at least in part upon the selected signal, the echo transfer function representing characteristics of an acoustic path between the loudspeaker and a far field microphone that is disposed at a greater distance from the speaker than the near field microphone;
determining an estimated echo based at least in part upon the echo transfer function;
subtracting the estimated echo from a signal received from the far field microphone, the subtracting effective to cancel an echo present in the signal received from the far end microphone.
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Accused Products
Abstract
A far end signal from a far end user and broadcasting the far end signal at a loudspeaker is received. A signal for use in an echo transfer function is determined, and the signal selected from between: the far end signal or an echo reference signal received from a near field microphone disposed in close proximity to the speaker. The near field microphone sensing the far end signal that is broadcast from the speaker while sensing the near-end speech and ambient noise at insignificant energy levels compared to the speaker signal. An echo transfer function is determined based at least in part upon the selected signal, and the echo transfer function represents characteristics of an acoustic path between the loudspeaker and a far field microphone that is disposed at a greater distance from the speaker than the near field microphone. An estimated echo is determined based at least in part upon the echo transfer function. The estimated echo is subtracted from a signal received from the far field microphone, the subtracting effective to cancel an echo present in the signal received from the far end microphone.
87 Citations
24 Claims
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1. A method, comprising:
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receiving a far end signal from a far end user and broadcasting the far end signal at a loudspeaker; determining a signal for use in estimating an echo transfer function, the signal selected from between;
the far end signal and an echo reference signal received from a near field microphone disposed in close proximity to the speaker, the determining the signal based at least in part on a comparison between the far end signal and the echo reference signal, the near field microphone sensing the far end signal that is broadcast from the speaker;determining an echo transfer function based at least in part upon the selected signal, the echo transfer function representing characteristics of an acoustic path between the loudspeaker and a far field microphone that is disposed at a greater distance from the speaker than the near field microphone; determining an estimated echo based at least in part upon the echo transfer function; subtracting the estimated echo from a signal received from the far field microphone, the subtracting effective to cancel an echo present in the signal received from the far end microphone. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. An apparatus, comprising,
a near field microphone for receiving sound from a speaker and producing an echo reference signal; -
a far field microphone that receives sound from the speaker; wherein the near field microphone and speaker are in close proximity; an echo reference control module configured to adaptively and determine an echo estimation signal, the echo estimation signal being selected from between;
an echo reference signal received from the near field microphone and a far end signal from a far end user, the determination of the echo estimation signal based at least in part on a comparison between the echo reference signal and the far end signal;an adaptation module that is configured to determine an echo transfer function based at least in part upon the selected echo estimation signal, and the adaptation module being further configured to determine an estimated echo based at least in part upon the echo transfer function; a summer that subtracts the estimated echo from a signal produced by the far field microphone to produce an echo canceled signal. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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Specification