Amazon Technologies, Inc.

Gurhan Saplakoglu

Alexander Kanaris

Berkant Tacer

A system configured to perform source classification using a continuously active beamformer and a classifier to improve beamforming. A device processes audio data representing sounds from multiple sound sources to determine a source direction corresponding to each detected sound source. For each audio frame, the classifier receives a source direction for each unknown sound source and uses the source direction to determine first spectral characteristics that are unique to the individual sound source. By comparing the first spectral characteristics to spectral characteristics associated with labeled sound sources, the device identifies a match and associates the source directions with a corresponding labeled sound source. For each labeled sound source, the classifier determines attributes of a corresponding signal, and the device uses these attributes to select a single sound source. Using a desired look direction associated with the selected sound source, the beamformer generates audio data representing desired speech.

Sound source classification and beamforming

A group of devices acquire audio input of a sound, such as speech, using respective microphones. For pairs of devices in the group, intensity of energy of audio input at each of the devices in the pair is used to determine first proximity data. Relative differences in time-of-arrival of the sound at the devices in the pair is used to determine second proximity data. The first and second proximity data are used to determine an estimated closest device of the pair with respect to the sound. Comparison of the first proximity data to the second proximity also allows a confidence value to be associated with the estimated closest device. The estimated closest device with the greatest confidence value may be selected for use to acquire audio input, present output, and so forth. Additional techniques such as beamforming techniques may be applied to the audio input from the selected device.

System to select audio from multiple connected devices

A system configured to perform distributed echo cancellation processing to attenuate feedback echo from occurring when two devices are acoustically coupled during a communication session. To reduce the feedback echo, one of the devices is configured as a hub device and receives microphone signals, synchronizes the microphone signals, and generates a mixed microphone signal. To enable distributed echo cancellation, the system includes bidirectional feedback link(s) between the hub device and each device synchronized with the hub device. For example, a first bidirectional feedback link sends a microphone signal from a second device to the hub device and sends the mixed microphone signal from the hub device to the second device, which the second device uses to perform echo cancellation. In addition, a second bidirectional feedback link sends a playback signal from the hub device to the second device and sends the output of echo cancellation back to the hub device.

Distributed feedback echo cancellation

A system configured to perform adaptive feedback reduction, such as howling suppression, to prevent feedback from occurring when two devices are acoustically coupled during a communication session. To reduce feedback between the acoustically coupled devices, a device monitors input audio data from a microphone and determines whether feedback is present in individual frequency subbands. For example, the device determines an expected value for a first subband using neighboring subbands (e.g., averaging subbands surrounding the first subband) and compares the expected value to an actual value for the first subband. If the actual value is noticeably higher than the expected value, the device determines that feedback is present in the first subband and attenuates the first subband. If the feedback is not present, the device passes the first subband without attenuation.

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Acton, MA, United States of America

Gurhan Saplakoglu