Step-size control for multi-channel acoustic echo canceller
AssigneeAmazon Technologies, Inc.
InventorAmit Singh Chhetri
Life of this patent
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Abstract
A multi-channel acoustic echo cancellation (AEC) system that includes a step-size controller that dynamically determines a step-size value for each channel and each tone index on a frame-by-frame basis. The system determines the step-size value based on a normalized squared cross-correlation (NSCC) between an estimated echo signal and an error signal, allowing the AEC system to converge quickly when an acoustic room response changes while providing stable steady-state error by avoiding misadjustments due to noise sensitivity and/or near-end speech. The step-size value can be determined using fractional weighting that takes into account a signal strength of each channel.
Claims20
A computer-implemented method implemented on a voice-controllable device, the method determining a step-size value of a first adaptive filter of the device, the method comprising:
- receiving a first reference audio signal that is sent from the device to a first loudspeaker for audio playback;
- receiving, from a microphone of the device, a first microphone audio signal representing audible sound output by the first loudspeaker;
- determining, using the first reference audio signal and the first adaptive filter that is configured to adjust according to an optimization algorithm, a first echo audio signal that is an estimated representation of a portion of the first microphone audio signal;
- determining a plurality of echo audio signals;
- determining a combined echo audio signal by summing the plurality of echo audio signals and the first echo audio signal;
- determining an error signal by subtracting the combined echo audio signal from the first microphone audio signal;
- determining a first normalized squared cross-correlation (NSCC) value between the error signal and the first echo audio signal;
- determining a first scale factor using the first NSCC value, the first scale factor becoming larger as the first NSCC value approaches a value of one;
- determining a first weight corresponding to a magnitude of the first reference audio signal;
- determining the step-size value by multiplying the first scale factor, the first weight and a nominal step-size value, the step-size value corresponding to the first reference audio signal;
- and
- providing the step-size value to the first adaptive filter.
A computer-implemented method, comprising:
- receiving a first reference signal corresponding to a first audio channel;
- receiving a second reference signal corresponding to a second audio channel;
- receiving a first audio input signal;
- determining, using a first adaptive filter and the first reference signal, a first echo signal that models a first portion of the first audio input signal;
- determining, using a second adaptive filter and the second reference signal, a second echo signal that models a second portion of the first audio input signal;
- combining the first echo signal and the second echo signal to generate a combined echo signal;
- determining an error signal by subtracting the combined echo signal from the first audio input signal;
- determining a first normalized squared cross-correlation (NSCC) value associated with the error signal and the first echo signal;
- determining a first scale factor based on the first NSCC value;
- and
- determining a first step-size value based on the first scale factor and a nominal step-size value, the first step-size value corresponding to the first reference signal.
A first device, comprising:
- at least one processor;
- a wireless transceiver;
- and
- a memory device including first instructions operable to be executed by the at least one processor to configure the first device to:
- receive a first reference signal corresponding to a first audio channel;
- receive a second reference signal corresponding to a second audio channel;
- receive a first input signal;
- determine, using a first adaptive filter and the first reference signal, a first echo signal that models a first portion of the first audio input signal;
- determine, using a second adaptive filter and the second reference signal, a second echo signal that models a second portion of the first audio input signal;
- combining the first echo signal and the second echo signal to generate a combined echo signal;
- determine an error signal by subtracting the combined echo signal from the first audio input signal;
- determine a first normalized squared cross-correlation (NSCC) value associated with the error signal and the first echo signal;
- determine a first scale factor based on the first NSCC value;
- and
- determine a first step-size value based on the first scale factor and a nominal step-size value, the first step-size value corresponding to the first reference signal.
Dependencies are inferred from the claim text.