Hearing Aid Noise Reduction via Phase Difference Estimation
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Solution Overview
Problem
Conventional hearing aid systems face difficulties in effectively reducing noise, which can lead to challenging hearing situations for users, despite their ability to compensate for hearing loss through frequency-dependent amplification.
Innovation Solution
The method involves a hearing aid system with multiple microphones, a sound estimator, and a digital signal processor that utilizes unbiased sound environment characteristics, specifically the inter-microphone phase difference, to apply frequency-dependent gain for improved noise suppression, allowing for directional noise reduction and enhanced signal-to-noise ratio estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional hearing aid systems use traditional noise reduction methods, then the device complexity remains manageable, but the noise reduction effectiveness is insufficient
Solution Approach 1:
The patent replaces traditional mechanical/acoustic noise reduction approaches with digital signal processing methods. Specifically, it uses digital microphones, analog-to-digital converters, and digital signal processors to implement sophisticated noise reduction algorithms including spectral subtraction, Wiener filtering, and adaptive noise cancellation, thereby achieving superior noise reduction effectiveness while maintaining device compactness
Solution Approach 2:
The patent changes the operating parameters of the hearing aid system by implementing frequency-dependent gain control and adaptive noise reduction algorithms that dynamically adjust processing parameters based on environmental conditions. The system modifies spectral characteristics, time constants, and gain values to optimize noise reduction performance across different listening scenarios
2Reliability
If hearing aid systems apply frequency-dependent amplification to compensate for hearing loss, then the hearing compensation is effective, but the noise reduction capability deteriorates
Solution Approach 1:
The patent segments the audio signal processing into distinct frequency bands using filter banks. Each frequency band is independently processed for both hearing compensation and noise reduction. This allows the system to apply frequency-dependent amplification for hearing loss compensation while simultaneously applying noise reduction algorithms to specific bands where noise is predominant, thereby achieving both goals without mutual interference
Solution Approach 2:
The patent applies different processing characteristics to different frequency regions and spatial locations. Hearing compensation gains are applied locally to frequency bands where the user has hearing deficits, while noise reduction is applied locally to frequency bands and spatial directions where noise is identified. This localized processing allows simultaneous optimization of both hearing compensation and noise reduction
3Reliability
If multiple microphones are used to improve noise suppression, then the noise reduction effectiveness is improved, but the device complexity increases
Solution Approach 1:
The patent merges the functions of multiple microphones into a unified beamforming and noise reduction system. Multiple microphone signals are combined using spatial processing techniques including beamforming, spatial filtering, and coherent-to-diffuse ratio estimation. This merging approach allows the system to achieve superior noise suppression through spatial selectivity while managing the complexity through integrated signal processing architecture
Solution Approach 2:
The patent implements a universal signal processing framework that handles multiple functions using the same microphone array. The same set of microphones is used for both noise reduction and for estimating sound environment characteristics such as reverberation, direct-to-reverberant ratio, and spatial distribution of sound sources. This multi-functionality reduces overall system complexity by avoiding dedicated hardware for each function
Data Source
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AI summary
A method of operating a hearing aid system in order to provide improved noise reduction and a hearing aid system (100) adapted to carry out the method.