Binaural Hearing Aid Spatial Signal Enhancement
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Solution Overview
Problem
Hearing impaired individuals face difficulties in understanding speech in noisy environments due to the internalization of sound by conventional binaural hearing aids, which fail to effectively separate and localize sound sources, leading to listening fatigue and reduced speech intelligibility.
Innovation Solution
A new binaural hearing aid system that filters monaural audio signals using Head-Related Transfer Functions (HRTFs) and interaural time and level differences to simulate spatial separation of sound sources, allowing users to perceive sounds as originating from specific directions, thereby enhancing sound source segregation and depth perception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional binaural hearing aids present sound to both ears, then hearing loss compensation is achieved, but sound sources cannot be separated and localized, leading to listening fatigue
Solution Approach 1:
The patent segments the audio signal into multiple frequency channels (typically 4-16 channels). Each channel is processed independently with different gain adjustments, allowing the system to create spatial separation effects while maintaining overall speech intelligibility. This segmentation enables the hearing aid to treat different frequency components differently, improving sound source separation.
Solution Approach 2:
The patent applies different processing characteristics to different frequency channels. Specifically, low-frequency channels receive different gain adjustments compared to high-frequency channels, creating local quality variations that simulate spatial separation. This local quality approach allows the system to maintain natural speech perception while providing directional cues for sound source separation.
2Reliability
If monaural audio signals are transmitted to the hearing aid, then signal to noise ratio is improved, but perceived spatial separation of multiple sound sources is lost
Solution Approach 1:
The patent transforms the monaural signal (one-dimensional) into a binaural signal with spatial characteristics (three-dimensional perception). By applying different gains to different frequency channels in each ear, the system creates virtual spatial separation, adding dimensional information to the monaural input signal without requiring multiple physical microphones.
Solution Approach 2:
The patent creates a virtual copy of the monaural signal for each ear, modifying each copy with different frequency-dependent gains. These modified copies are then presented to the respective ears, creating the perception of spatial separation. The system effectively copies the signal and applies spatial transformation through differential filtering and gain adjustment.
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 system improves the user's ability to separate and focus on desired sound sources, enabling better understanding of speech in noisy conditions by providing perceived spatial separation of sound sources, reducing listening fatigue and enhancing speech intelligibility.
Implementation Method 1
a binaural filter with a transfer function of a Head-Related Transfer Function (HRTF) imparting a perceived direction of arrival to a sound source
Implementation Method 2
filtered with binaural filters in such a way that a user perceives the signals to be emitted by respective sound sources positioned in different spatial positions
Implementation Method 3
the sound presented to one ear is phase shifted relative to the sound presented to the other ear, and additionally, the sound presented to one ear may be set to a different level relative to the sound presented to the other ear
Data Source
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AI summary
A new binaural hearing aid system is provided with a hearing aid in which signals that are received from external devices, 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 with binaural filters in such a way that a user perceives the signals to be emitted by respective sound sources positioned in different spatial positions in the sound environment of the user, whereby improved spatial separation of the different sound sources is facilitated.