Hearing Device Microphone Noise Rejection via Signal Correlation
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Solution Overview
Problem
Hearing devices face challenges in accurately rejecting inherent noise from microphones, which can be amplified along with quiet signals, impairing sound quality, especially at low signal levels, due to the difficulty in distinguishing inherent noise from other low-level signals.
Innovation Solution
A method using a first and second microphone to generate signals, calculating the correlation between them, and rejecting inherent noise based on this correlation to minimize noise amplification in the output sound signal, employing techniques like Wiener filters and spectral subtraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If algorithms are applied to reject inherent noise based on measured or estimated sound levels and noise levels, then inherent noise rejection is improved, but the ability to distinguish inherent noise from other low-level signals deteriorates
Solution Approach 1:
The patent segments the noise rejection problem by using multiple microphones to capture different signal components. By analyzing the correlation between signals from different microphones, the system can identify and separate inherent noise from other low-level signals, solving the distinction problem that plagues single-microphone approaches.
Solution Approach 2:
The patent introduces correlation analysis as an intermediary mechanism between raw microphone signals and noise rejection processing. This intermediary step provides objective information about the nature of low-level signals, enabling the system to distinguish inherent noise from other signals without relying solely on subjective noise level estimates.
2Power
If directional microphonics are applied to amplify quiet signals, then signal amplification is improved, but inherent noise amplification worsens
Solution Approach 1:
The patent employs feedback through correlation analysis between multiple microphone signals. This feedback mechanism continuously monitors the relationship between signals and dynamically adjusts processing to amplify desired quiet signals while suppressing amplified inherent noise, resolving the contradiction between signal enhancement and noise suppression.
Solution Approach 2:
The patent changes the parameter being monitored from absolute noise levels to correlation between signals. This parameter transformation enables the system to distinguish between amplified quiet signals (which maintain correlation) and amplified inherent noise (which shows reduced correlation), allowing selective amplification without noise degradation.
3Adaptability or versatility
If signal processing is applied to compensate for impaired hearing, then hearing compensation is improved, but sound quality deteriorates due to noise amplification
Solution Approach 1:
The patent segments the hearing processing function into separate components: one handling hearing compensation based on individual hearing losses, and another handling noise suppression based on correlation analysis. This segmentation allows each component to operate optimally without the other compromising performance, maintaining sound quality while providing hearing compensation.
Solution Approach 2:
The patent introduces correlation-based noise identification as an intermediary layer between signal amplification and output. This intermediary filters out amplified inherent noise before it reaches the final output, ensuring that hearing compensation processing does not degrade sound quality by transmitting amplified noise to the user.
Data Source
AI summary
A method for rejecting inherent noise of a microphone arrangement that includes a first microphone and a second microphone. The first microphone generates a first microphone signal from an ambient sound signal and the second microphone generates a second microphone signal from the ambient sound signal. A measure of correlation between the first microphone signal and the second microphone signal is ascertained, and inherent noise of the first microphone and/or of the second microphone in the first or second microphone signal is rejected on the basis of the measure of correlation.