Hearing Aid Eardrum Sound Pressure Estimation
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Solution Overview
Problem
Current hearing aids struggle to accurately measure sound pressure levels at the eardrum, as existing methods like couplers and probe tubes are inconvenient and indirect methods, such as measuring ear canal levels, require reliable estimation techniques to determine eardrum levels.
Innovation Solution
A method using a hearing aid with a processor, a first microphone capturing ear-canal sounds, and an acoustical model combined with a statistical model to estimate sound pressure levels at the eardrum by minimizing differences between observed and modeled values, allowing for accurate representation and calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct measurements are performed using probe tubes inserted close to the eardrum, then measurement precision is improved, but device complexity and ease of operation deteriorate
Solution Approach 1:
The patent uses an inward-facing microphone as an intermediary device positioned in the ear canal to capture sound pressure levels indirectly. This microphone serves as a mediator between the hearing aid and the eardrum, allowing measurements without direct probe tube insertion near the eardrum. The system processes signals from this intermediary microphone to estimate eardrum sound pressure levels, thus improving ease of operation while maintaining acceptable measurement precision.
2Ease of operation
If inward-facing microphones are positioned at a distance from the eardrum for user comfort, then ease of operation is improved, but measurement precision deteriorates
Solution Approach 1:
The patent replaces the mechanical measurement approach (probe tubes physically positioned near the eardrum) with an acoustic modeling approach. Instead of relying on the physical position of the microphone for accurate measurement, the system uses acoustic models to simulate and estimate the sound pressure levels at the eardrum based on measurements from the inward-facing microphone. This substitution allows the microphone to be positioned for user comfort while maintaining measurement precision through computational methods.
Solution Approach 2:
The patent changes the measurement parameters by using acoustic model parameters (transfer functions, ear canal geometry, boundary conditions) rather than relying solely on the physical position of the microphone. By adjusting and optimizing these model parameters to match individual user characteristics, the system can accurately estimate eardrum sound pressure levels even when the microphone is positioned at a comfortable distance, thus resolving the contradiction between ease of operation and measurement precision.
3Measurement precision
If acoustic models with many parameters are used to improve estimation accuracy, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent applies partial action by using a simplified version of the full acoustic model that includes only the most critical parameters necessary for accurate estimation. Rather than implementing a complete physics-based acoustic model with all possible parameters, the system selects and implements only the essential parameters that have the greatest impact on estimation accuracy. This approach maintains measurement precision while reducing device complexity and computational requirements.
Data Source
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AI summary
A method at hearing aid and a hearing aid including a processor, a first microphone, a second microphone; wherein the first microphone is arranged to capture ear-canal sounds, and wherein the second microphone is arranged to capture ambient sounds; comprising: an acoustical model (511) configured to generate first values (hk) for the multiple frequency channels based on first parameters (G, A, l); and a statistical model (512) configured to generate second values (rk) for the multiple frequency channels based on values of second parameters (s1, s2, ··· , sn) and a set of basis vectors (u1, u2, ··· , un). An optimizer (509) is configured to obtain an optimized set of parameter values ({G, A, l, s1, s2, ··· , sn}*) including values of the first parameters and values of the second parameters; wherein the optimized set of parameter values is obtained by minimizing a difference between the first sound pressure levels (robs) and a combination of the first values (rk) and the second values (hk). An advantage is that sound pressure levels at the eardrum of the wearer of hearing aid can be accurately determined using a hearing aid with a microphone arranged to capture ear-canal sounds only at a distance from the ear drum.