Hearing Aid Monaural Signal Localization via Spatial Cue Filtering
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Solution Overview
Problem
Hearing impaired individuals face challenges in localizing sound sources due to internalized sound reproduction in hearing aids, leading to difficulty in understanding speech in noise environments, which results in listening fatigue and potential abandonment of the hearing aid.
Innovation Solution
A hearing aid system that filters monaural audio signals to introduce interaural time and level differences, simulating Head Related Transfer Functions (HRTFs) to externalize sound sources, allowing users to perceive sound sources as originating from specific directions and distances, thereby enhancing sound localization and speech intelligibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hearing aids reproduce sound internally to compensate for hearing loss, then audibility of speech is improved, but sound source localization ability deteriorates
Solution Approach 1:
The system separates the monaural signal processing into two independent paths: one path processes the signal for hearing loss compensation, while the other path processes the same signal for spatial cue extraction and localization. This segmentation allows both functions to operate simultaneously without interfering with each other, resolving the contradiction between improving audibility and maintaining localization ability.
Solution Approach 2:
The patent introduces an intermediary processing stage that extracts spatial cues (interaural time differences, interaural level differences, and spectral cues) from the monaural signal and applies them as filtering operations. This intermediary mechanism bridges the gap between monaural input and binaural output, enabling sound source localization to be restored while maintaining hearing loss compensation.
2Reliability
If hearing aids provide internalized sound reproduction, then speech intelligibility is improved, but speech understanding in noise deteriorates
Solution Approach 1:
The system dynamically changes the parameters of the filtering operation based on the extracted spatial cues. By adjusting the filter characteristics according to the interaural time differences, interaural level differences, and spectral cues, the system optimizes speech understanding in noise environments while maintaining overall speech intelligibility.
3Reliability
If monaural signals are transmitted to hearing aids, then signal to noise ratio is improved, but sound source localization is lost
Solution Approach 1:
The patent introduces asymmetric filtering operations that create artificial interaural time differences and interaural level differences from the monaural signal. This asymmetric processing simulates the natural asymmetric acoustic cues that the human auditory system uses for localization, thereby restoring sound source localization capability while maintaining the high signal-to-noise ratio benefits of monaural transmission.
Data Source
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AI summary
A hearing aid is provided in which signals that are received from an external device, such as a spouse microphone, a media player, a hearing loop system, a teleconference system, a radio, a TV, a telephone, a device with an alarm, etc., are filtered in such a way that a user can localize the sound source.