Noise adaptive beamforming for microphone arrays

Abstract

The subject disclosure is directed towards a noise adaptive beamformer that dynamically selects between microphone array channels, based upon noise energy floor levels that are measured when no actual signal (e.g., no speech) is present. When speech (or a similar desired signal) is detected, the beamformer selects which microphone signal to use in signal processing, e.g., corresponding to the lowest noise channel. Multiple channels may be selected, with their signals combined. The beamformer transitions back to the noise measurement phase when the actual signal is no longer detected, so that the beamformer dynamically adapts as noise levels change, including on a per-microphone basis, to account for microphone hardware differences, changing noise sources, and individual microphone deterioration.

Description

technical field [0001] The present invention relates to discarding degrading microphone signals by not using noisy signals. Background technique [0002] Microphone arrays capture signals from multiple sensors and process those signals to improve the signal-to-noise ratio. In conventional beamforming, the general approach is to combine signals from all sensors (channels). A typical use of beamforming is to provide the combined signal to a speech recognizer for speech recognition. [0003] In practice, however, this approach actually degrades overall performance, and indeed, sometimes performs even worse than individual microphones. This is partly because of individual hardware differences between microphones, which cause different microphones to pick up different types and different amounts of noise. Another factor is that the noise source may change dynamically. Furthermore, different microphones deteriorate differently, which again leads to reduced performance. Conte...

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Problems solved by technology

[0003] In practice, however, this approach actually degrades overall performance, and indeed, sometimes performs even worse than a single microphone

This is partly due to individual hardware differences between microphones, which cause dif

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