Acoustic echo cancellation (AEC) rate adaptation
AssigneeCirrus Logic, Inc.
InventorsKhosrow Lashkari, Justin Allen
Life of this patent
Estimating the term…
Abstract
Step size can be used to slow or freeze the adaptive filter to improve AEC system performance, such as during double talk events. An AEC control system may be used to adjust the step size based on an echo-to-disturbance energy ratio (EDER). The algorithm adjusts the step size to lower the adaptation rate when the EDER is small (or the combination of the near signal and noise is large compared to the echo) and raise the adaptation rate when the EDER is large (echo is large compared to a combination of near signal and noise).
Claims20
A method for echo cancellation in an audio system having a transducer and a microphone, comprising:
- generating an echo-cancelled output signal from a microphone input signal and a transducer output signal, wherein the echo-cancelled output signal is generated using an adaptive filter;
- determining an echo-to-disturbance energy ratio by comparing an energy of the microphone input signal and an energy of the echo-cancelled output signal;
- and
- adjusting a step size of the adaptive filter used to converge on the echo-cancelled output signal based, at least in part, on the echo-to-disturbance energy ratio, wherein the step size is an echo-signal-to-noise-ratio (ESNR)-based variable step size (EVSS) μESNR computed according to:
- μ
- EVSS
- =
- μ
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An apparatus, comprising:
- an audio controller configured to perform steps comprising:
- generating an echo-cancelled output signal from a microphone input signal and a transducer output signal, wherein the echo-cancelled output signal is generated using an adaptive filter;
- determining an echo-to-disturbance energy ratio by comparing an energy of the microphone input signal and an energy of the echo-cancelled output signal;
- and
- adjusting a step size of the adaptive filter used to converge on the echo-cancelled output signal based, at least in part, on the echo-to-disturbance energy ratio, wherein the step size is an echo-signal-to-noise-ratio (ESNR)-based variable step size (EVSS) μESNR computed according to:
- μ
- EVSS
- =
- μ
-
- (
- P
- in
- -
- P
- out
- )
- P
- in
- +
- (
- R
- -
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- .
An acoustic echo cancellation (AEC) system, comprising:
- an adaptive filter configured to modify an input microphone signal based on a plurality of filter coefficients to obtain an echo-cancelled output signal;
- a step size controller coupled to the adaptive filter and configured to adjust an adaptation rate of the adaptive filter based, at least in part, on an echo-to-disturbance energy ratio computed from the input microphone signal, the echo-cancelled output signal, and a desired echo reduction level, wherein the adaptation rate is based on a step size that is an echo-signal-to-noise-ratio (ESNR)-based variable step size (EVSS) μESNR computed according to:
- μ
- EVSS
- =
- μ
-
- (
- P
- in
- -
- P
- out
- )
- P
- in
- +
- (
- R
- -
- 1
- )
-
- P
- out
- .
Dependencies are inferred from the claim text.