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US 9,997,151 B1Granted
Multichannel acoustic echo cancellation for wireless applications
AssigneeAmazon Technologies, Inc.
InventorsRobert Ayrapetian, Philip Ryan Hilmes, Yuwen Su
Life of this patent
Estimating the term…
Abstract
An acoustic echo cancellation (AEC) system that detects and compensates for differences in delay times between the AEC system and a set of wireless speakers. The filter coefficients used for AEC are adjusted based on the determined delay time to correct for frequency domain signal rotation.
Claims20
A method, comprising:
- transmitting an audio reference signal to a wireless speaker;
- storing samples of the audio reference signal;
- outputting audible sound from the wireless speaker;
- receiving a first signal from a first microphone, the first signal including a portion of the audible sound;
- comparing the first signal with the stored samples of the audio reference signal to determine a first time offset between the first signal and the audio reference signal, the first time offset corresponding to a first propagation delay time, the comparing comprising one of:
- performing a cross-correlation of the first signal with the stored samples to determine the first time offset, or
- performing a normalized least mean squares analysis of the first signal and the stored samples to determine the first time offset;
- determining a first filter coefficient for a first adaptive filter based on an exponential function of at least the first propagation delay time;
- and
- reproducing the audio reference signal as a first reproduced reference signal so as to have a second time offset relative to the first signal, wherein the second time offset is less than the first time offset.
7 more elements
A computing device comprising:
- a processor;
- a memory including instructions operable to be executed by a processor that configure the processor to:
- wirelessly transmit a first audio reference signal to a first sound reproduction device that is independent of the computing device;
- receive a first signal from a microphone, the first signal including a first portion of the first audio reference signal as output by the first sound reproduction device;
- perform a time-domain cross-correlation of the first audio reference signal and the first signal, or perform a time-domain normalized least mean squares analysis of the first audio reference signal and the first signal;
- determine a first propagation delay time between the first audio reference signal and the first signal based on the time-domain cross-correlation or the time-domain normalized least mean squares analysis;
- determine a first filter coefficient of a first adaptive filter based at least in part on the first propagation delay time, wherein the first filter coefficient is determined using an exponential function;
- input the first audio reference signal into the first adaptive filter, wherein the first adaptive filter applies the first filter coefficient to the first audio reference signal and outputs a first echo signal corresponding to a first estimate of a first portion of the first audio reference signal included in the first signal;
- and
- subtract the first echo signal from the first signal as a first output signal.
7 more elements
A method performed by a computing device, comprising:
- wirelessly transmitting a first audio reference signal to a first sound reproduction device that is independent of the computing device;
- receiving a first signal from a microphone, the first signal including a first portion of the first audio reference signal as output by the first sound reproduction device;
- performing a time-domain cross-correlation of the first audio reference signal and the first signal, or performing a time-domain normalized least mean squares analysis of the first audio reference signal and the first signal;
- determining a first propagation delay time between the first audio reference signal and the first signal based on the time-domain cross-correlation or the time-domain normalized least mean squares analysis;
- determining a first filter coefficient of a first adaptive filter based at least in part on the first propagation delay time, wherein the first filter coefficient is determined using an exponential function;
- imputing the first audio reference signal into the first adaptive filter, wherein the first adaptive filter applies the first filter coefficient to the first audio reference signal and outputs a first echo signal corresponding to a first estimate of a first portion of the first audio reference signal included in the first signal;
- and
- subtracting the first echo signal from the first signal as a first output signal.
5 more elements
Dependencies are inferred from the claim text.