Binaural Hearing Aid Bilateral Compression ILD Preservation
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Solution Overview
Problem
Binaural hearing aid systems face challenges in accurately determining and preserving interaural level differences (ILDs) due to non-linear gain-amplification, which distorts binaural spatial cues, especially in noisy environments, as traditional microphone placements fail to capture acoustical contributions from the outer ear and concha.
Innovation Solution
The method involves picking up sound pressure inside the ear canal using in-ear microphones to generate microphone signals, transmitting contralateral audio data wirelessly, estimating interaural level differences, and adjusting gains based on level-versus-gain characteristics to preserve ILDs between the signals, ensuring accurate representation of individual head-related transfer functions and spatial cues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional microphone placement (at or behind the ear) is used, then device simplicity is maintained, but accurate capture of acoustical contributions from outer ear and concha is lost
Solution Approach 1:
Instead of placing the microphone outside the ear (traditional approach), the invention inverts the placement by positioning the microphone inside the ear canal. This reversal allows the microphone to capture sound after it has already interacted with the outer ear and concha, thereby accurately obtaining HRTFs and ILDs that would otherwise require complex external microphone arrays.
2Device complexity
If unilateral dynamic range compression is applied, then individual hearing aid processing is simplified, but interaural level differences are distorted
Solution Approach 1:
The invention applies bilateral dynamic range compression where each hearing aid not only processes its own microphone signal but also receives and processes contralateral audio data from the opposite hearing aid. This feedback loop allows the system to estimate and preserve ILDs by coordinating compression parameters between both ears, thereby maintaining binaural spatial cues while still providing individualized hearing aid processing.
3Measurement precision
If in-ear microphones are used to capture accurate HRTFs, then spatial cue accuracy is improved, but feedback risk increases due to proximity of microphone and receiver
Solution Approach 1:
The invention addresses the feedback problem by utilizing the binaural dimension - each hearing aid processes both its own (ipsilateral) and the opposite ear's (contralateral) audio data. This dimensional approach allows the system to maintain in-ear microphones for accurate spatial cue capture while using contralateral signal processing to manage and reduce feedback risks through coordinated bilateral compression.
Data Source
AI summary
The present disclosure relates to a method of performing bilateral dynamic range compression of first and second microphone signals generated by first and second hearing devices, respectively, of a binaural hearing system. The method comprises to pick-up sound pressure inside an ear canal of the user's left or right ear by a first microphone to generate a first microphone signal in response to incoming sound and pick-up sound pressure inside an ear canal of the user's opposite ear by a second microphone to generate a second microphone signal in response to the incoming sound.