Hearing Aid Spatial Localization via ITE Microphone Integration
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Solution Overview
Problem
Hearing aid users experience poor sound source localization and increased cognitive loading due to internalized sound reproduction, leading to listening fatigue and potential removal of the device, as existing behind-the-ear (BTE) hearing aids fail to accurately replicate the spatial cues essential for sound localization.
Innovation Solution
Incorporating an In-The-Ear (ITE) microphone positioned in the outer ear or ear canal to record spatial information, combined with conventional BTE microphones, and using adaptive signal processing to preserve and enhance spatial cues, thereby approximating the Head-Related Transfer Function (HRTF) for improved sound localization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional BTE microphones are used positioned behind the ear, then the device is easy to wear and comfortable, but sound source localization is poor and spatial cues are lost
Solution Approach 1:
The patent combines conventional BTE microphones positioned behind the ear with additional ITE microphones positioned in the ear canal or at the ear canal entrance. This merging of multiple microphone systems allows the hearing aid to capture both the comfortable behind-ear sound field and the spatially-accurate in-ear sound field, thereby improving sound source localization while maintaining wearing comfort.
Solution Approach 2:
The patent introduces an intermediary signal processing system that combines outputs from BTE microphones and ITE microphones. This intermediary processing layer synthesizes a sound signal that preserves spatial cues from the ITE microphones while incorporating the comfortable acoustic field captured by the BTE microphones, thus resolving the contradiction between localization accuracy and wearing comfort.
2Reliability
If sound is reproduced to improve hearing clarity, then speech intelligibility is improved, but sound sources are internalized and localization ability deteriorates
Solution Approach 1:
The patent applies different quality characteristics to different parts of the sound reproduction system. The BTE microphones capture the general sound field for speech intelligibility enhancement, while the ITE microphones capture localized spatial cues for accurate sound source localization. This local quality differentiation allows simultaneous improvement of both speech intelligibility and localization accuracy.
Solution Approach 2:
The patent segments the sound reproduction function into two distinct pathways: one pathway processes signals from BTE microphones for speech clarity and intelligibility, while another pathway processes signals from ITE microphones for spatial localization. This segmentation allows independent optimization of each function without compromising the other.
3Measurement precision
If multiple microphones are added to preserve spatial cues, then sound localization is improved, but device complexity increases
Solution Approach 1:
The patent designs the ITE microphone component to serve multiple functions: it captures spatial cues for localization, provides feedback for stability, and can be integrated with existing BTE microphone processing chains. This multi-functionality reduces the need for entirely separate processing systems, thereby limiting the increase in device complexity despite adding multiple microphones.
4Measurement precision
If ITE microphone is positioned in the ear canal to capture spatial information, then localization is improved, but feedback risk increases and stable gain is reduced
Solution Approach 1:
The patent utilizes feedback from the ITE microphone positioned in the ear canal to detect and suppress feedback signals. By monitoring the acoustic field at the ear canal entrance or inside the ear canal, the system can identify feedback paths and apply appropriate suppression, thereby maintaining stable gain despite the proximity of the ITE microphone to the sound output.
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
The solution enhances sound localization capabilities, reduces cognitive loading, and increases maximum stable gain while minimizing feedback, thereby improving user experience and retention of the hearing aid.
Implementation Method 1
The input to the hearing consists of two signals, namely the sound pressures at each of the eardrums
Implementation Method 2
The transmission of a sound wave from a sound source positioned at a given direction and distance in relation to the left and right ears of the listener is described in terms of two transfer functions, one for the left ear and one for the right ear, that include any linear distortion, such as coloration, interaural time differences and interaural spectral differences. Such a set of two transfer functions, one for the left ear and one for the right ear, is called a Head-Related Transfer Function (HRTF)
Implementation Method 3
the processor is further configured for processing an audio signal from the at least one ITE microphone and the audio signal from the at least one BTE sound input transducer in such a way that the hearing loss compensated output signal substantially preserves spatial cues
Implementation Method 4
an output transducer for conversion of the hearing loss compensated output signal to an auditory output signal that can be received by the human auditory system
Data Source
AI summary
A BTE hearing aid includes a BTE hearing aid housing, at least one BTE sound input transducer, a processor configured to generate a hearing loss compensated output signal, a sound signal transmission member for transmission of a signal from a sound output of the BTE hearing aid housing to an ear canal of a user at a second end of the sound signal transmission member, an earpiece configured to be inserted in the ear canal, an output transducer, and an ITE microphone housing accommodating at least one ITE microphone, wherein the ITE microphone housing is configured to be positioned in an outer ear, wherein the processor is further configured for processing an audio signal from the at least one ITE microphone and an audio signal from the at least one BTE sound input transducer in such a way that the hearing loss compensated output signal substantially preserves spatial cues.