Hearing Aid Directional Microphone Adaptive Delay Control
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Solution Overview
Problem
The existing directional microphone systems in hearing aids are ineffective due to their dependence on the precise positioning of microphones, which is affected by factors like hairstyle and head shape, leading to suboptimal directivity and articulation index (AI-DI) performance across varying wearing positions and environments.
Innovation Solution
The use of cross-correlation analysis to determine the effective time delay between microphones, allowing for adaptive internal delay settings based on the individual wearing position and hearing situation, combined with histogram analysis for stable results and frequency-dependent adjustments to account for diffraction and reflection effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fixed basic time delay is set for directional microphone system, then optimal directivity is achieved for specific wearing position, but performance degrades when wearing position deviates from ideal position
Solution Approach 1:
The patent implements dynamic adjustment of the basic time delay parameter in the directional microphone system. Instead of using a fixed time delay optimized for a specific wearing position, the system continuously adapts the time delay parameter based on the actual wearing position detected through classification algorithms. This allows the directional characteristics to be optimized in real-time for different wearing positions, resolving the contradiction between achieving optimal directivity for a specific position and maintaining performance across varying positions.
Solution Approach 2:
The patent changes the basic time delay parameter dynamically based on the wearing position. By detecting the actual wearing position and adjusting the time delay parameter accordingly, the system maintains optimal directional characteristics across different wearing scenarios. This parameter adaptation resolves the contradiction by allowing the system to achieve optimal directivity for each specific wearing position rather than being fixed for one position.
2Manufacturing precision
If KEMAR measurements are used to set basic time delay, then reference directivity is achieved, but individual variations in head shape and hairstyle cause deviations from optimal performance
Solution Approach 1:
The patent enables the hearing aid system to automatically determine and adapt to the individual user's wearing position without requiring manual adjustment or precise manufacturing fitting. The classification algorithms analyze the acoustic environment and automatically adjust the basic time delay parameter to match the user's actual wearing position and head characteristics. This self-adjusting capability resolves the contradiction between precise manufacturing settings and individual variations in head shape and hairstyle.
Solution Approach 2:
The system uses feedback from the acoustic environment and classification algorithms to continuously monitor and adjust the basic time delay parameter. By detecting the actual wearing position and comparing it with the optimal position, the system automatically adjusts the time delay to compensate for individual variations in head shape and hairstyle. This feedback mechanism resolves the contradiction by adapting the manufacturing precision to individual user characteristics.
3Measurement precision
If directional microphone system is configured for specific wearing position, then speech intelligibility is optimized for that position, but system complexity increases to accommodate position detection and adjustment
Solution Approach 1:
The patent integrates the wearing position detection and time delay adjustment functions into the existing hearing aid signal processing architecture. The classification algorithms that analyze the acoustic environment for hearing aid control are extended to also determine wearing position. This multi-functional approach allows the system to achieve optimized speech intelligibility across different wearing positions without significantly increasing device complexity, as the same processing resources serve multiple purposes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables optimized directivity and improved speech understanding in changing environments by adapting the directional microphone system to individual positions and situations, maintaining high AI-DI performance regardless of wearing position deviations.
Implementation Method 1
The internal time delay in at least one microphone signal generated by one of the two microphones is then set as a function of the external delay determined by means of the correlation analysis.
Implementation Method 2
histogram analysis to determine a resulting effective time delay at which a largest number of the determined cross-correlation functions have their maximum
Implementation Method 3
frequency-dependent adjustments to account for diffraction and reflection effects
Implementation Method 4
frequency-dependent adjustments to account for diffraction and reflection effects
Data Source
Figure 1
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Figure 4
AI summary
The hearing aid (HA1) has a microphone (F1,F2), where microphone signal (SF1,SF2) originates from a microphone and another microphone signal (SB1,SB2) originates from latter microphone (B1,B2). A control unit (C1,C2) is provided for adjusting a time delay (T-i1,T-i2) depending on the value of the cross correlation of the two microphone signals. The classifier is provided for determining a hearing situation in which the hearing aid is formed in a straight line, where setting of the time delay is a function of the hearing situation. Independent claims are also included for the following: (1) a method for operating a hearing aid with a directional microphone system; and (2) a method for operating a hearing aid device with a hearing aid supported on the left ear of a user.