Hearing Device Real Ear Measurement Correction
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Solution Overview
Problem
Existing methods for real ear measurements (REMs) in hearing devices are often inaccurate due to factors like microphone placement, leading to inconsistent sound pressure at the eardrum and improper hearing aid fitting.
Innovation Solution
The system automatically corrects REMs by producing a sound signal through a hearing device receiver in the ear canal, sensing the sound pressure signal with an inward-facing microphone, transforming it into a frequency response signal, detecting local minima, calculating spectral flatness, and applying acoustic correction using an estimated transfer function when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional REM measurement methods are used with probe tube microphones, then sound pressure at the eardrum can be measured, but measurement accuracy deteriorates due to microphone placement errors and artifacts
Solution Approach 1:
The patent uses an inward-facing microphone as an intermediary measurement device positioned within the hearing device itself, rather than using a separate probe tube microphone. This intermediary approach eliminates the need for precise probe tube placement and removes artifacts caused by probe tube interactions with the ear canal, thereby improving both measurement accuracy and reliability
Solution Approach 2:
The patent creates a digital copy or model of the ear canal acoustics through transfer function estimation. By measuring at a known position and mathematically modeling the acoustic transfer function, the system replicates what would be measured at the eardrum position without physically placing a microphone there, thus avoiding placement errors and artifacts
2Measurement precision
If probe tube microphones are used for REM measurements, then sound pressure can be sensed, but device complexity increases due to precise placement requirements and calibration procedures
Solution Approach 1:
The hearing device performs self-measurement using its own inward-facing microphone and speaker. The device generates test signals through its own speaker and measures the response through its own microphone, eliminating the need for external probe tube equipment and complex calibration procedures. The system serves itself, reducing both device complexity and procedural complexity
Solution Approach 2:
The patent transforms the measurement approach by changing the parameter of microphone orientation from outward-facing (traditional probe tube) to inward-facing (toward the eardrum). This parameter change fundamentally simplifies the measurement system by using the hearing device's own components, eliminating placement precision requirements and calibration complexity
3Measurement precision
If acoustic correction is applied using transfer function estimation, then measurement accuracy improves, but processing complexity increases
Solution Approach 1:
The patent performs preliminary estimation of the transfer function during the fitting process before final hearing aid programming. By pre-calculating and storing the transfer function characteristics, the system avoids complex real-time processing during actual hearing aid operation, reducing processing complexity while maintaining measurement accuracy
Solution Approach 2:
The patent replaces complex mechanical measurement systems (probe tubes, external measurement equipment) with computational methods (transfer function estimation, digital signal processing). This substitution of mechanical complexity with computational algorithms improves measurement accuracy while the algorithms can be efficiently implemented in the hearing device's processor
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 provides more accurate real ear measurements, reduces the need for precise probe tube placement, and improves sound quality by correcting measurement artifacts and ensuring better fitting of hearing devices.
Implementation Method 1
A sound signal is produced through a receiver of a hearing device placed inside an ear canal of a user
Implementation Method 2
A sound pressure signal is sensed, in response to the sound signal, using a microphone placed inside the ear canal
Data Source
AI summary
Disclosed herein are systems and methods for automatic correction of real ear measurements (REMs). A sound signal is produced through a receiver of a hearing device, and a sound pressure signal is sensed using a microphone placed inside the ear canal. The sound pressure signal is transformed to obtain a frequency response signal, a local minimum of the frequency response signal is detected above a programmable frequency level, and a spectral flatness of the frequency response signal is calculated in a selected frequency band surrounding the local minimum. If the spectral flatness is greater than a selected threshold value, acoustic correction is applied to the frequency response in the selected frequency band using an estimated transfer function to obtain a corrected sound pressure frequency response. The corrected sound pressure frequency response is used to modify, or make a recommendation to modify, a physical or operational characteristic of the hearing device.