Reducing acoustic feedback over variable-delay pathway
AssigneeLogMeln, Inc.
InventorsCarlotta Anemüller, Florian Heese, Patrick Vicinus
Life of this patent
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Abstract
A technique for reducing acoustic feedback in audio communications includes measuring variations in round-trip delay over an audio signal pathway. The technique varies a delay interval of an adjustable-delay element in real time based on the measured variations in round-trip delay, effectively canceling the delay variations. Further techniques are disclosed for detecting and eliminating howling frequencies which arise as a result of acoustic feedback in the audio signal pathway.
Claims19
A method of reducing acoustic feedback in audio communications, the method comprising:
- measuring changes in round-trip delay along an audio signal pathway that extends from a microphone of a first computing device, to a computer network, over the computer network to a second computing device, to a speaker of the second computing device, and through an acoustic medium from the speaker back to the microphone, the microphone having an output that produces a microphone signal;
- modeling the audio signal pathway with a path emulator that includes (i) an adaptive filter configured to emulate an impulse response of the audio signal pathway but not the changes in round-trip delay and (ii) an adjustable-delay element, coupled in series with the adaptive filter and configured to emulate the changes in round-trip delay based on the measured changes;
- and
- generating, by the path emulator in response to receipt of an audio signal by the path emulator, a prediction signal that emulates effects of the audio signal pathway on the audio signal, the audio signal generated as a difference between the microphone signal and the prediction signal and providing a representation of the microphone signal corrected for acoustic feedback.
A computerized apparatus, comprising control circuitry that includes a set of processors coupled to memory, the control circuitry constructed and arranged to:
- measure changes in round-trip delay along an audio signal pathway that extends from a microphone of a first computing device, to a computer network, over the computer network to a second computing device, to a speaker of the second computing device, and through an acoustic medium from the speaker back to the microphone, the microphone having an output that produces a microphone signal;
- model the audio signal pathway with a path emulator that includes (i) an adaptive filter configured to emulate an impulse response of the audio signal pathway but not the changes in round-trip delay and (ii) an adjustable-delay element, coupled in series with the adaptive filter and configured to emulate the changes in round-trip delay based on the measured changes;
- and
- generate, by the path emulator in response to receipt of an audio signal by the path emulator, a prediction signal that emulates effects of the audio signal pathway on the audio signal, the audio signal generated as a difference between the microphone signal and the prediction signal and providing a representation of the microphone signal corrected for acoustic feedback.
A computer program product including a set of non-transitory, computer-readable media having instructions which, when executed by control circuitry of a computerized apparatus, cause the computerized apparatus to perform a method for reducing acoustic feedback in audio communications, the method comprising:
- measuring changes in round-trip delay along an audio signal pathway that extends from a microphone of a first computing device, to a computer network, over the computer network to a second computing device, to a speaker of the second computing device, and through an acoustic medium from the speaker back to the microphone, the microphone having an output that produces a microphone signal;
- modeling the audio signal pathway with a path emulator that includes (i) an adaptive filter configured to emulate an impulse response of the audio signal pathway but not the changes in round-trip delay and (ii) an adjustable-delay element, coupled in series with the adaptive filter and configured to emulate the changes in round-trip delay based on the measured changes;
- and
- generating, by the path emulator in response to receipt of an audio signal by the path emulator, a prediction signal that emulates effects of the audio signal pathway on the audio signal, the audio signal generated as a difference between the microphone signal and the prediction signal and providing a representation of the microphone signal corrected for acoustic feedback.
Dependencies are inferred from the claim text.