Adaptive Wind Noise Suppression in Hearing Aid Systems
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing hearing aid systems face inefficiencies in wind noise suppression, particularly with methods relying on Wiener filters that require noise spectrum estimation and struggle with time-varying wind noise, and subtraction filters that inadequately suppress uncorrelated wind noise.
Innovation Solution
A processing unit with a first and second microphone, A/D converters, a subtraction node, and an adaptive filter, where the adaptive filter uses linear prediction theory and the Least Mean Square algorithm to subtract wind noise components, maintaining sound fidelity and adapting to fluctuating signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a Wiener filter is used for wind noise suppression, then the system can process signals through frequency domain transformation and spatial filtering, but the system reliability deteriorates because it requires noise spectrum estimation which is difficult and unreliable especially when wind noise spectrum is time varying
Solution Approach 1:
The patent extracts and processes signals from multiple microphones through spatial filtering to separate wind noise components from desired acoustic signals. By using beam forming on multi-microphone inputs, the system extracts wind noise characteristics without requiring explicit noise spectrum estimation, thereby improving reliability while maintaining wind noise suppression capability
Solution Approach 2:
The system implements feedback mechanisms where the output of the spatial filter and subsequent processing stages are used to continuously adapt and refine wind noise suppression. The processed signals from multiple microphones are fed back through the processing chain, allowing the system to dynamically adjust to time-varying wind noise conditions without compromising reliability
2Device complexity
If a subtraction filter is used to suppress wind noise, then the system structure is simplified, but the wind noise suppression efficiency deteriorates because uncorrelated wind noise from multiple microphones is not efficiently suppressed
Solution Approach 1:
The patent combines signals from multiple microphones through spatial filtering and beam forming before applying subtraction operations. By merging the multi-microphone signals in the spatial domain first, the system creates correlated representations of wind noise that can be efficiently suppressed, thereby improving suppression efficiency without significantly increasing overall system complexity
Solution Approach 2:
The system dynamically processes signals by applying adaptive spatial filtering and time-varying processing stages rather than simple static subtraction. The processing adapts to the statistical properties of the input signals, allowing efficient suppression of uncorrelated wind noise while maintaining a relatively simple device structure
3Ease of operation
If noise spectrum estimation is performed for Wiener filter operation, then wind noise suppression can be applied, but the measurement precision deteriorates because the noise spectrum is difficult to estimate accurately
Solution Approach 1:
The patent introduces spatial filtering and beam forming as intermediary processing stages that transform the raw multi-microphone signals into processed representations with enhanced wind noise characteristics. These intermediary processed signals serve as better inputs for subsequent suppression stages, eliminating the need for direct noise spectrum estimation and thereby maintaining wind noise suppression functionality without sacrificing measurement precision
Data Source
AI summary
A processing unit that adaptively suppresses wind noise in a hearing aid is provided. The processing unit (100) comprises a first microphone (105) and a second microphone (106). The analog signal from the first microphone is converted to a first digital signal (107) in a first A/D converter (113) and the analog signal from the second microphone is converted to a second digital signal (108) in a second A/D converter (114). The output of the first A/D converter is operationally connected to a first input of a subtraction node (111). The output of the second A/D converter is operationally connected to the input of an adaptive filter (109). The output of the adaptive filter (109) is branched and in a first branch operationally connected to the second input of the subtraction node (111) and in a second branch operationally connected to the input of the remaining signal processing in the hearing aid. The output from the subtraction node (111) is operationally connected to a control input of the adaptive filter (109). The invention also relates to a hearing aid system having such a processing unit and a method of adaptive wind noise suppression in a hearing aid system.