Hearing Aid Reference Microphone Selection
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Solution Overview
Problem
Conventional hearing aids face challenges in effectively isolating target sound sources from background noise using beamforming techniques, as the selection of reference microphones is often fixed and does not adapt to changing acoustic environments or frequency bands, leading to suboptimal noise reduction and sound localization.
Innovation Solution
A hearing aid system with multiple microphones that dynamically selects a reference microphone for each frequency band based on directional data such as directivity index or front-back ratio, using adaptive beamforming techniques like MVDR to ensure undistorted sound from the target direction while attenuating noise, and allows for user-defined target direction input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed reference microphone is used for beamforming, then the device complexity is reduced, but the noise reduction performance and sound localization accuracy deteriorate in changing acoustic environments
Solution Approach 1:
The patent implements dynamic selection of reference microphones based on acoustic environment analysis. The system continuously evaluates directional characteristics and automatically switches between different microphones as reference sources, transforming the static beamforming system into a dynamic one that adapts to changing acoustic conditions, thereby maintaining reliable noise reduction performance without excessive complexity
Solution Approach 2:
The system changes the parameter of reference microphone selection based on frequency band and acoustic environment. By analyzing directional data such as directivity index and front-back ratio across different frequency bands, the system selects optimal reference microphones, achieving improved noise reduction and sound localization through parameter adaptation rather than increasing overall system complexity
2Reliability
If adaptive beamforming with frequency-band-specific reference microphones is implemented, then noise reduction performance is improved, but the device complexity increases
Solution Approach 1:
The patent segments the audio frequency spectrum into multiple frequency bands and applies different reference microphone selections for each band. This segmentation allows the system to optimize noise reduction for specific frequency ranges independently, improving overall noise reduction performance while managing complexity through localized optimization rather than global complexity
Solution Approach 2:
The system performs preliminary analysis of directional characteristics and pre-selects optimal reference microphones for each frequency band based on criteria such as directivity index and front-back ratio. This preliminary action enables the beamforming system to quickly adapt to acoustic environments without requiring complex real-time calculations during audio processing, thereby improving noise reduction performance while controlling computational complexity
3Measurement precision
If the reference microphone selection is adapted to different frequency bands, then sound localization accuracy is improved, but the ease of operation deteriorates
Solution Approach 1:
The patent implements self-service operation where the hearing aid automatically analyzes acoustic environments and selects optimal reference microphones for each frequency band without user intervention. The system uses built-in algorithms to evaluate directional data and make intelligent decisions, improving sound localization accuracy while maintaining ease of operation through automated decision-making that eliminates complex user configuration requirements
Data Source
AI summary
A hearing aid adapted for being worn by a user comprises at least two microphones, providing respective at least two electric input signals representing sound; a filter bank converting the at least two electric input signals into signals as a function of time and frequency; a directional system connected to said at least two microphones and being configured to provide a filtered signal in dependence of said at least two electric input signals and fixed or adaptively updated beamformer weights. At least one direction to a target sound source is defined as a target direction. For each frequency band, one of said at least two microphones is selected as a reference microphone, thereby providing a reference input signal for each frequency band. The reference microphone for a given frequency band may be selected in dependence of directional data related to directional characteristics of the at least two microphones.