Microphone Array Noise Reduction via Energy Difference Attenuation
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Solution Overview
Problem
Current noise reduction methods in hearing devices are hindered by inaccurate reference signal estimates, leading to inappropriate filtering and degradation in output quality, particularly at low Signal-to-Noise Ratios (SNR).
Innovation Solution
A noise reduction method that senses sound sources using an arrangement of microphones to produce left and right microphone output signals, determining their magnitudes or powers, and attenuating signals based on the difference and sum of these values to improve SNR without relying on complex reference signal estimates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Voice Activity Detection is used to estimate noise reference signals, then noise reduction processing can be implemented, but the reference signal estimates become inaccurate leading to inappropriate filtering and degradation in output quality
Solution Approach 1:
The patent introduces an intermediary mechanism (energy difference calculation between target and non-target directions) to bridge the gap between microphone signals and noise estimation. Instead of directly using Voice Activity Detection on microphone signals, the system calculates energy differences as an intermediate step to derive more accurate noise reference signals, thereby resolving the contradiction between implementing noise reduction and maintaining estimation accuracy
Solution Approach 2:
The patent transforms the approach by changing the parameter used for noise estimation from direct Voice Activity Detection outputs to energy difference values derived from comparing target and non-target directional signals. This parameter change enables more reliable noise reference signal generation that maintains accuracy across varying SNR conditions
2Reliability
If complex reference signal estimation techniques are used, then noise reduction can be achieved, but the system complexity and error susceptibility increase
Solution Approach 1:
The patent extracts only the essential energy difference information from the microphone signals rather than processing complete reference signals. By taking out just the critical energy comparison between target and non-target directions, the system achieves reliable noise reduction while minimizing processing complexity and error susceptibility
Solution Approach 2:
Instead of trying to directly estimate noise from complex reference signals, the patent inverts the approach by calculating what remains after removing target signal energy from total energy. This inversion simplifies the processing while improving reliability by focusing on the energy difference that directly represents noise
Data Source
AI summary
Noise reduction methods and systems for reducing unwanted sounds in signals received from an arrangement of microphones are disclosed, the method including the steps of: sensing sound sources distributed around a specified target direction by way of an arrangement of microphones to produce left and right microphone output signals; determining the magnitude or power of the left and right microphone signals; attenuating the signals based on the difference of the magnitudes or powers or values derived from the magnitudes or powers of the left and right microphone signals.