Hearing Aid Interaural Coherence Noise Suppression
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Solution Overview
Problem
Existing hearing aid systems are inefficient in suppressing noise from interfering speakers, which hinders speech intelligibility for hearing-impaired individuals in noisy environments.
Innovation Solution
A method and system that utilize time-frequency domain processing and interaural coherence analysis to calculate a gain value based on three contiguous ranges of interaural coherence values, allowing for adaptive noise suppression by distinguishing between distant and nearby speakers, and accounting for their orientation relative to the user.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional noise suppression methods are used in hearing aid systems, then general background noise is reduced, but noise from interfering speakers is not efficiently suppressed
Solution Approach 1:
The patent segments the noise suppression problem by dividing the audio signal processing into distinct stages: initial noise suppression for general background noise, followed by a secondary interference speaker suppression stage. This segmentation allows each stage to target specific types of noise separately, with the first stage handling ambient noise and the second stage specifically addressing interfering speakers using interaural coherence analysis.
Solution Approach 2:
The patent introduces a new dimension for noise suppression by utilizing interaural coherence (spatial correlation between left and right ear signals) as an additional parameter beyond traditional spectral analysis. This dimensional approach allows the system to distinguish between noise sources based on their spatial characteristics, enabling effective suppression of interfering speakers while preserving speech intelligibility.
2Object-affected harmful factors
If aggressive noise suppression is applied, then background noise is reduced, but speech clarity and intelligibility deteriorate
Solution Approach 1:
The patent implements dynamic gain adjustment based on interaural coherence values. The suppression gain is not fixed but varies dynamically according to the coherence measurement, allowing the system to adaptively suppress noise while preserving speech signals. This dynamic approach ensures that speech intelligibility is maintained by adjusting suppression strength based on real-time coherence analysis.
Solution Approach 2:
The patent changes the parameter of noise suppression by introducing interaural coherence as a control parameter. Instead of using fixed or purely spectral-based suppression, the system varies the suppression gain based on the coherence parameter, which reflects the spatial relationship between noise sources and the user's ears. This parameter change enables selective suppression that preserves speech clarity.
3Object-affected harmful factors
If simple gain adjustment is used, then processing is computationally efficient, but noise suppression from interfering speakers is insufficient
Solution Approach 1:
The patent performs preliminary noise suppression before the main interference speaker suppression stage. This preliminary action reduces general background noise first, simplifying the subsequent task of identifying and suppressing interfering speakers. By preparing the signal in advance through initial suppression, the overall processing complexity is managed while achieving better final results.
Solution Approach 2:
The patent uses interaural coherence as an intermediary parameter to bridge simple gain adjustment and complex noise suppression. The coherence value serves as a mediator that guides the suppression gain calculation, providing a computationally efficient way to estimate spatial characteristics without requiring full spectral analysis or complex source separation algorithms.
Data Source
AI summary
A method of processing signals in a hearing aid system (200, 300) comprises the steps of transforming two audio signals to the time-frequency domain, calculating the interaural coherence, deriving a first gain based on the interaural coherence, applying the first gain value in the amplification of the time-frequency signals, and transforming the signals back into the time domain for further processing in the hearing aid. The first gain value as a function of the value representing the interaural coherence comprises three contiguous ranges for the values representing the interaural coherence, where the maximum slope in the first and third range are smaller than the maximum slope in the second range, the first range comprising low interaural coherence values, the third range comprising high interaural coherence values, and the second range comprising intermediate interaural coherence values. The invention further provides a hearing aid system (200, 300) adapted for suppression of interfering speakers.