Acoustic echo canceller
AssigneeQUALCOMM Incorporated
InventorWay-Shing Lee
Life of this patent
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Abstract
An apparatus and method for echo cancellation is presented. The echo canceller comprises an adaptive filter that tracks the impulse response of the echo path and produces an estimate of the echo. Filter adaptation is controlled by a controller based on the rate of the far-end speech signal, the rate of the near-end signal, an acoustic loss measure, and a double talk hangover indicator. The controller may also comprise a step size adaptation unit for determining the adaptation step size of the adaptive filter. In addition, the controller may comprise a noise replacement unit, which controls replacement of the echo residual signal with comfort noise to ensure echo is completely rejected when only the far-end speaker is talking.
Claims32
An apparatus for canceling echo in a system where echo of a far-end speech signal is combined with a signal from a near-end, comprising:
- an adaptive filter having a plurality of filter tap coefficients for generating an echo estimate signal, said filter tap coefficients updated in response to a first control signal;
- a controller for generating said first control signal in accordance with the rate of said far-end speech signal and the rate of a near-end signal which combines said signal from said near-end and said echo signal, said rates being ones of a predetermined set of rates in a variable rate communications system;
- comprising:
- energy computation unit adapted to measure the energy of input signals;
- background noise estimator adapted to determine the noise energy when no speech is present;
- and
- a rate estimator adapted to determine data rates of the far-end and near-end signals;
- and
- a summer for subtracting said echo estimate signal from said near-end signal to generate an echo residual signal.
An apparatus for canceling echo in a system where echo of a far-end speech signal is combined with a signal from a near-end, comprising:
- means for generating a first control signal in accordance with the rate of said far-end speech signal and the rate of a near-end signal which combines said signal from said near-end and said echo signal, said rates being ones of a predetermined set of rates in a variable rate communications system;
- means for updating a plurality of filter tap coefficients of an adaptive filter based on said first control signal;
- means for generating an echo estimate signal using said adaptive filter;
- and
- means for subtracting said echo estimate signal from said near-end signal to generate an echo residual signal.
Dependencies are inferred from the claim text.