Adaptive Beamformer for Partner Microphone Noise Reduction
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Solution Overview
Problem
Current partner microphone systems face challenges in maintaining a high signal-to-noise ratio (SNR) due to variable microphone positioning and changing noise environments, such as in car or plane cabins, where the beamformer noise reduction system is less effective.
Innovation Solution
A dedicated beamformer-noise reduction system is implemented in the partner microphone unit, which includes an adaptive multi-input beamformer filtering unit, a voice activity detector, and a noise power spectral density estimator. This system is calibrated offline and can update its noise reduction parameters based on the presence or absence of the target voice signal, adapting to changes in microphone position and noise levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a beamformer noise reduction system is employed to retrieve the target voice signal from noise background, then the signal-to-noise ratio is improved, but the system effectiveness decreases when the microphone axis is not fixed or points away from the wearer's mouth
Solution Approach 1:
The patent implements an adaptive beamformer that dynamically adjusts its parameters based on the detected position of the target sound source. The system continuously monitors the acoustic environment and reconfigures the beamforming weights to track the wearer's mouth position, ensuring optimal noise reduction performance regardless of microphone orientation or movement.
Solution Approach 2:
The system incorporates feedback mechanisms where the detected sound source position and noise characteristics are fed back to continuously optimize the beamformer parameters. This closed-loop control enables the system to adapt to changing conditions such as microphone movement, clothing deformation, and varying speech positions, maintaining high signal-to-noise ratio throughout.
2Ease of operation
If the partner microphone system is attached casually to variable surfaces such as clothes on the chest, then the ease of operation is improved, but the position and direction of the clip relative to the wearer's mouth changes over time, reducing beamformer performance
Solution Approach 1:
The system is designed to be dynamic and adaptive rather than relying on fixed positioning. The beamformer continuously tracks the target sound source position and adjusts its beam pattern accordingly, allowing the microphone to be attached casually to variable surfaces while maintaining optimal performance through real-time parameter adaptation.
Solution Approach 2:
The system changes its operational parameters (beamforming weights, noise reduction coefficients) based on the detected acoustic environment and target position. This parameter adaptation allows the system to compensate for physical movements and positioning variations, maintaining high signal-to-noise ratio despite casual attachment to moving surfaces like clothing.
3Measurement precision
If multiple microphones are used to enable beamforming and noise reduction, then the signal-to-noise ratio can be improved, but the device complexity increases
Solution Approach 1:
The system segments the signal processing tasks into distinct functional blocks: beamforming stage, noise reduction stage, and voice activity detection stage. This modular segmentation allows each component to be optimized independently and simplifies the overall system design while achieving high signal-to-noise ratio through coordinated operation of multiple microphones.
Solution Approach 2:
The patent implements a multi-functional signal processing system where the same microphone array and processing unit handle multiple functions: directional beamforming, adaptive noise reduction, voice activity detection, and source localization. This multi-functionality reduces overall device complexity by consolidating capabilities into a unified system rather than requiring separate dedicated components for each function.
Data Source
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AI summary
The application relates to a partner microphone unit comprising a) a multitude microphones for picking up a sound from the environment providing corresponding electric input signals, each comprising a target signal component and a noise signal component; b) a multi-input unit noise reduction system for providing an estimate S of the target sound s comprising the person's voice and comprising a multi-input beamformer filtering unit coupled to said input units and configured to determine filter weights for providing a beamformed signal, wherein signal components from other directions than a direction of the target signal source are attenuated, whereas signal components from the direction of the target signal source are left un-attenuated; c) antenna and transceiver circuitry for establishing an audio link to another device; and wherein the multi-input beamformer filtering unit comprises an adaptive beamformer. An improved quality of a target signal from a speaker or communication partner is provided. The invention may e.g. be used in hearing aids, headsets, ear phones, active ear protection systems or combinations thereof.