Hearing Aid ITE Microphone Spatial Cue Preservation
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Solution Overview
Problem
Hearing aid users experience difficulty in localizing sound sources due to internalized sound reproduction, leading to listening fatigue and reduced speech intelligibility in noisy environments, as existing hearing aids fail to accurately replicate the spatial cues and Head-Related Transfer Functions (HRTFs) of natural hearing.
Innovation Solution
The new hearing aid design incorporates an ITE microphone positioned in the outer ear, either at the entrance to the ear canal or inside it, to capture spatial cues and combine these signals with BTE microphone signals using adaptive cue filters, ensuring that the output signals preserve directional information and minimize feedback, thereby approximating the individual's HRTFs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If hearing aids use conventional microphone positioning behind the ear, then the device structure is simple and feedback is minimized, but spatial cues are lost and sound localization ability deteriorates
Solution Approach 1:
The patent combines BTE microphones (behind the ear) with ITE microphones (in the ear canal) into a hybrid system. The BTE microphones capture sound with reduced feedback, while the ITE microphones capture spatial cues and HRTF information. The signals are processed together through adaptive filtering to achieve both feedback reduction and spatial cue preservation.
Solution Approach 2:
The patent divides the microphone system into separate functional components: BTE microphones positioned behind the ear for primary sound capture with minimal feedback, and ITE microphones positioned in the ear canal for spatial cue capture. Each microphone type serves a specific function, and their signals are later integrated through adaptive processing.
2Productivity
If hearing aids amplify sound signals, then speech intelligibility is improved, but feedback increases and stabilizes poorly
Solution Approach 1:
The patent introduces adaptive cue filters as an intermediary processing stage between the microphones and the hearing aid output. These filters process the microphone signals to preserve spatial cues while allowing sufficient amplification for speech intelligibility. The ITE microphone signals serve as a reference for the adaptive filtering, enabling the system to maintain spatial information while achieving the required gain.
3Reliability
If hearing aids reproduce sound internally, then the hearing loss compensation is effective, but sound localization ability deteriorates and listening fatigue increases
Solution Approach 1:
The patent uses adaptive filtering with the ITE microphone signals as a reference to create a feedback mechanism that preserves spatial cues. The adaptive cue filters continuously adjust their parameters to match the HRTF characteristics captured by the ITE microphones, ensuring that the reproduced sound maintains directional information while providing effective hearing loss compensation.
Data Source
AI summary
A hearing aid includes: a cue filter having an input that is provided with an output from the BTE sound input transducer; an adaptive feedback canceller configured to provide an output modelling a feedback path between the output transducer and the BTE sound input transducer, wherein the output modelling the feedback path is provided to a subtractor for subtraction of the output modelling the feedback path from the output of the BTE sound input transducer to obtain a difference, the subtractor outputting the difference to the cue filter; and a feedback and cue controller connected to the adaptive feedback canceller and the cue filter, wherein the feedback and cue controller is configured to control the cue filter to reduce a difference between an output of the ITE microphone and a combined output that is obtained using at least the cue filter.