Electro-acoustic Feedback for Ear Occlusion Reduction
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Solution Overview
Problem
Existing occlusion reduction methods in hearing aids and similar devices, such as vents and deep earmold insertion, either compromise sound amplification or cause physical discomfort, and fail to effectively manage feedback and signal overload.
Innovation Solution
An electro-acoustic system with a negative-feedback loop that includes a microphone, electronic circuits for signal processing and combination, and a receiver, which estimates signal levels to control processing and reduce occlusion effects by modifying signals within specific frequency ranges, thereby minimizing discomfort and amplification limitations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a vent is used to reduce occlusion effect, then naturalness of voice is restored, but hearing aid amplification is limited due to oscillations from positive feedback
Solution Approach 1:
The patent implements a negative feedback loop that senses the output signal from the hearing aid processor and feeds it back through a filter and summer to subtract from the original output signal. This negative feedback mechanism counteracts the positive feedback oscillations that occur through the vent, allowing the vent to remain open for naturalness while preventing harmful oscillations that would limit amplification.
Solution Approach 2:
The patent introduces an intermediary negative feedback path that acts as a mediator between the hearing aid processor output and the final output signal. This intermediary path processes the signal through filtering and summation to cancel out the unwanted positive feedback components, enabling the system to maintain both vent openness and amplification stability.
2Object-affected harmful factors
If earmold is inserted deeper into ear canal to reduce occlusion effect, then occlusion effect is reduced at source, but physical discomfort increases
Solution Approach 1:
The patent replaces the mechanical solution of deep earmold insertion with an electro-acoustic negative feedback system. Instead of physically modifying the earmold insertion depth to reduce occlusion, the system uses electronic signal processing to cancel occlusion effects, thereby maintaining comfort while achieving the desired reduction in occlusion.
3Power
If signal level is increased to improve amplification, then hearing aid performance is improved, but receiver overloading occurs
Solution Approach 1:
The negative feedback loop continuously monitors the output signal level and adjusts the feedback accordingly. When signal levels become too high and approach receiver overload thresholds, the feedback mechanism automatically reduces the gain, preventing receiver overloading while allowing maximum safe amplification to be utilized.
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 effectively reduces occlusion effects by minimizing signal levels and adapting to changes, enhancing the natural sound perception and reducing discomfort, while maintaining robustness against feedback and noise.
Implementation Method 1
a microphone for generating an internal signal from an acoustical signal
Implementation Method 2
a receiver for generating an acoustical signal from the receiver signal
Data Source
AI summary
A system and method that reduces the perceptual effect resulting from ear occlusion include an electro-acoustic feedback network that produces phase canceling sounds in the ear, where a receiver and a microphone are located. A control mechanism controls the response of the feedback network to minimize distortion in the ear while maintaining a desired frequency response for external signals. Devices producing the external signal include hearing aids, personal sound devices, in ear monitors, communications headsets and hearing protectors. The integration of the above with these devices improves a user's perception of their own voice.