Dual Dipole Omnidirectional Microphone Array for Hearing Aids
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Solution Overview
Problem
Conventional directional microphone arrays in hearing aids suffer from sensitivity and phase mismatch issues, which worsen over time, and are not optimized for in-situ placement on users, leading to inferior directional performance in noisy environments.
Innovation Solution
A dual dipole omnidirectional (DDO) directional microphone array configuration with two dipole microphones positioned symmetrically around an omnidirectional microphone, where the omnidirectional microphone is placed between them, allowing for robust directional performance despite sensitivity and phase variations, and optimized using in-situ measurements to maintain performance across age and placement variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional directional microphone arrays are used in hearing aids, then directional sound reception is provided, but sensitivity and phase mismatch issues worsen over time leading to inferior directional performance
Solution Approach 1:
The patent combines omnidirectional and bidirectional microphones into a hybrid array configuration. This merging of different microphone types creates a system where the omnidirectional microphone captures sound from all directions while the bidirectional microphones provide directional sensitivity, compensating for individual microphone mismatches through the combined array response.
Solution Approach 2:
The hybrid microphone array serves multiple functions simultaneously: it provides omnidirectional sound capture for ambient noise, bidirectional capture for speech from specific directions, and creates a robust system that maintains directional performance despite individual microphone variations. The system is optimized for in-situ placement on the user's head, adapting to real-world conditions.
2Measurement precision
If directional microphones are optimized for free-field conditions, then theoretical directional performance is achieved, but in-situ placement on users results in inferior performance
Solution Approach 1:
The patent applies parameter changes by optimizing the microphone array specifically for in-situ conditions rather than free-field conditions. This involves adjusting the spacing, orientation, and signal processing parameters to account for the proximity of the user's head, ear canal, and surrounding anatomy, thereby achieving superior directional performance in the actual wearing environment.
3Reliability
If higher-order directionality is achieved through complex microphone arrays, then directional performance improves, but device size and complexity increase
Solution Approach 1:
The patent segments the directional microphone function into multiple simpler components: omnidirectional microphones for ambient sound capture and bidirectional microphones for directional sensitivity. This segmentation allows each microphone type to perform its specialized function while the combined array achieves higher-order directionality without requiring a single complex microphone design.
Data Source
AI summary
Disclosed herein, among other things, are methods and apparatus for an directional microphone arrays for hearing assistance devices. In various embodiments, the present subject matter provides a microphone array system for receiving sounds including a first directional microphone, a second directional microphone and an omnidirectional microphone. The first directional microphone has a first directional axis in a first direction, and the second directional microphone has a second directional axis that is collinear with the first direction and pointing in the same direction as the first direction. The omnidirectional microphone has a sound sampling position that is a disposed between the first directional microphone and the second directional microphone, and the omnidirectional microphone sound sampling position is on or about the first directional axis. Weighted outputs of the first directional microphone, second directional microphone, and omnidirectional microphone are processed to provide a second order directional microphone system, according to various embodiments.