Hearing Aid Low-Frequency Transducer for Active Occlusion Cancellation
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Solution Overview
Problem
Hearing aid users experience occlusion issues with own voice sounds being perceived distorted and loud, and body-generated sounds like chewing becoming intrusive, which existing solutions like increasing vent size degrade audiological performance.
Innovation Solution
A hearing aid design with a separate loudspeaker optimized for low frequencies, located near the eardrum, generates an anti-occlusion signal using an inward-facing microphone to measure occlusion, complemented by a traditional loudspeaker for mid/high frequencies, ensuring effective occlusion cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the vent size is increased to reduce occlusion, then occlusion is reduced, but noise reduction and low frequency amplification performance deteriorate
Solution Approach 1:
The patent divides the audio output function into two separate transducers: a first transducer for general audio output and a second transducer specifically for low frequency anti-occlusion signal generation. This segmentation allows each transducer to be optimized for its specific function, with the second transducer dedicated to generating cancellation signals for body-generated sounds while the first transducer maintains audiological performance.
Solution Approach 2:
The patent applies local quality by making the second transducer specifically optimized for low frequency response to generate anti-occlusion signals, while the first transducer handles the full frequency range for normal hearing aid function. This localized optimization allows effective occlusion cancellation without compromising overall audiological performance.
2Device complexity
If a single loudspeaker is used for both audio output and anti-occlusion, then device complexity is reduced, but anti-occlusion effectiveness deteriorates
Solution Approach 1:
The patent segments the audio output system into two distinct transducers with different functions: the first transducer for general audio reproduction and the second transducer specifically for generating anti-occlusion signals. This functional segmentation ensures that the anti-occlusion transducer can be optimized for low frequency efficiency without compromising the audio quality from the first transducer.
Solution Approach 2:
Instead of using the primary audio transducer for anti-occlusion cancellation, the patent introduces a second transducer whose primary purpose is anti-occlusion signal generation. This inverted approach ensures that the anti-occlusion function does not interfere with the primary audio output function, resolving the conflict between the two requirements.
3Reliability
If the vent size is reduced to improve noise reduction, then noise reduction performance is improved, but low frequency sound build-up increases
Solution Approach 1:
The patent extracts the low frequency anti-occlusion function from the primary audio transducer and assigns it to a second dedicated transducer. This extraction allows the vent size to be reduced for improved noise reduction performance while the second transducer compensates for body-generated sound build-up by generating active cancellation signals.
Solution Approach 2:
The patent implements an active feedback mechanism where a microphone detects body-generated sounds in the ear canal, and the second transducer generates anti-phase signals to cancel these sounds. This feedback loop effectively counteracts the low frequency sound build-up that would otherwise result from the reduced vent size.
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 solution provides improved audiological performance by reducing occlusion while maintaining noise reduction and low-frequency amplification, enhancing user comfort and discreetness.
Implementation Method 1
a second output transducer located in said ITE-part and configured to play sound to the user and to provide said acoustic anti-occlusion signal
Implementation Method 2
an ear canal input transducer located in said ITE-part and configured to provide an electric ear canal input signal representing sound in said ear canal
Data Source
Figure 1
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Figure 2B
AI summary
A hearing aid configured to be worn by a user at or in an ear of the user, comprises • an ITE-part adapted for being located at or in an ear canal of the user; • at least one first input transducer configured to provide corresponding at least one first electric input signal representing sound; • a hearing aid processor configured to provide a processed signal in dependence of said at least one electric input signal; • a first output transducer configured to play sound to the user in dependence of said processed signal, or a signal dependent thereon; • an active occlusion cancellation system (AOCS) for providing an acoustic anti-occlusion signal configured to cancel or diminish a sense of occlusion of the user when the user is speaking, or otherwise is using his or her voice, or when otherwise moving the jaws; wherein the active occlusion cancellation system comprises • an ear canal input transducer located in said ITE-part and configured to provide an electric ear canal input signal representing sound in said ear canal, when the user wears the hearing aid; • an ear canal sound estimation unit (ECSE) configured to estimate sound in said ear canal and to provide an electric anti-occlusion signal in dependence of said electric ear canal input signal and said processed signal; and • a second output transducer located in said ITE-part configured to play sound to the user and to provide said acoustic anti-occlusion signal in dependence of said electric anti-occlusion signal, wherein said second output transducer is specifically adapted to provide sound at frequencies below a threshold frequency. A method of operating a hearing aid is further disclosed.