Adaptive phase difference based noise reduction for automatic speech recognition (ASR)

摘要

Embodiments of a system and method for adapting a phase difference-based noise reduction system are generally described herein. In some embodiments, spatial information associated with a first and second audio signal are determined, wherein the first and second audio signals including a target audio inside a beam and noise from outside the beam. A signal-to-noise ratio (SNR) associated with the audio signals is estimated. A mapping of phase differences to gain factors is adapted for determination of attenuation factors for attenuating frequency bins associated with noise outside the beam. Spectral subtraction is performed to remove estimated noise from the single-channel signal based on a weighting that affects frequencies associated with a target signal less. Frequency dependent attenuation factors are applied to attenuate frequency bins outside the beam to produce a target signal having noise reduced.

主权项

1. An adaptive phase difference-based noise reduction system, comprising:
a first channel for receiving a first audio signal at a first microphone; a second channel for receiving a second audio signal at a second microphone, the first and second audio signals including a target audio inside a beam and noise from outside the beam; a processor, coupled to the first and second channel, the processor arranged to:
determine spatial information associated with the first audio signal and with the second audio signal;adjust phase differences by applying an adjustment for a phase difference greater than π equal to −2π+ the phase difference greater than π and applying an adjustment for a phase difference less than −π equal to 2π+the phase difference less than −π; toestimate a signal-to-noise ratio (SNR) on a single-channel signal derived from the first and second audio signals using the determined spatial information;adapt a mapping of the adjusted phase differences to gain factors for determination of frequency dependent attenuation factors for attenuating frequency bins associated with noise outside the beam, wherein to adapt the mapping of the adjusted phase differences to gain factors includes:
calculating phase difference errors for the frequency bins to be respectively equal to an absolute value of a phase difference divided by a phase-threshold vector component and subtracting a beam factor, components of a phrase-threshold vector corresponding to the frequency bins; andclamping negative phase difference error values to zero to prevent frequency bins inside an inner portion of the beam from being attenuated; andapply the frequency dependent attenuation factors to attenuate frequency bins outside the beam to produce a target signal having noise reduced.