Hearing Aid Receiver as Microphone for Occlusion Measurement
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Solution Overview
Problem
Existing hearing aids face challenges in accurately measuring the occlusion effect, which causes users' voices to sound hollow or boomy due to ear canal occlusion, and current methods do not effectively utilize the hearing aid's receiver as a transducer for sound pressure measurement, leading to sensitivity and frequency response issues.
Innovation Solution
A system within the hearing aid that switches between amplification and occlusion measurement modes, using a filter bank to split electrical signals into bands and equalize the receiver's signal to compensate for its frequency-dependent transfer function, allowing for in-situ occlusion effect measurement by comparing signals from the microphone and receiver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the hearing aid uses the receiver as a transducer for sound pressure measurement, then the measurement can be performed in-situ with existing components, but the receiver has frequency-dependent transfer function that degrades measurement accuracy
Solution Approach 1:
The patent applies parameter changes by modifying the electrical signal parameters to compensate for the receiver's frequency-dependent characteristics. Specifically, the system applies frequency-dependent gain adjustments and phase corrections to the receiver output signal, transforming it to match the expected microphone response across different frequencies. This allows the receiver to be used for accurate measurements despite its non-ideal frequency response.
2Object-affected harmful factors
If a vent is introduced in the ear mould to reduce occlusion effect, then the user experience improves, but energy loss and acoustic feedback increase
Solution Approach 1:
The patent implements feedback by using the receiver as a microphone to detect sound pressure in the ear canal, then using this information to adjust the hearing aid's output signal. The system measures the actual occlusion effect in real-time and applies compensatory processing to the amplified audio signal, creating a closed-loop control system that reduces the occlusion effect dynamically while monitoring for feedback conditions.
Solution Approach 2:
The patent replaces the purely mechanical approach of vent design with an electronic signal processing solution. Instead of relying on physical vent geometry to control sound flow, the system uses digital signal processing to simulate the effect of a vent by selectively attenuating low-frequency components in the amplified signal, thereby reducing the occlusion effect without the energy losses associated with physical vents.
3Object-affected harmful factors
If the ear mould is inserted deeper to block more vibrating wall, then the occlusion effect decreases, but the stability and amplification of the hearing aid are compromised
Solution Approach 1:
The patent replaces the mechanical solution of deeper insertion with an electronic signal processing approach. The system uses the receiver-as-microphone to measure sound pressure and applies digital filtering to reduce the occlusion effect in the amplified signal, eliminating the need to compromise insertion depth for stability while still achieving occlusion effect reduction through software-based frequency management.
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
Enables a simple and accurate measurement of the occlusion effect using the hearing aid's own voice as a sound source, reducing equipment requirements and minimizing noise and spectral leakage, thereby improving user experience by optimizing vent diameter and reducing feedback.
Implementation Method 1
the receiver being adapted for, when in said occlusion measurement mode, transforming the acoustic sound level in the ear canal into a second electrical signal
Implementation Method 2
The invention is further related to a method for measuring the occlusion effect in situ by a hearing aid receiver... signal processing means comprising a filter bank with means for splitting an electrical signal into different frequency bands
Data Source
Figure 1
Figure 2
Figure 3a~3e
AI summary
A hearing aid (1) adapted for operation in a sound amplification mode and for operation in an occlusion measurement mode, said hearing aid comprising a microphone (10) adapted for transforming an acoustic sound level external to a hearing aid users ear canal (4) into a first electrical signal which is guided to an A/D converter forming a first digitized electrical signal. The hearing aid comprise signal processing means with a filter bank (41, 42) with means for splitting an electrical signal into frequency bands,and a receiver (20) adapted for generating acoustic sounds in the ear canal of a user when in said amplification mode, and adapted for transforming the acoustic sound level in the ear canal into a second electrical signal, and further comprising means for directing the second electrical signal obtained by the receiver to an A/D converter (34) forming a second digitized electrical signal. When the hearing aid is in occlusion measurement mode the filter bank can split the first and the second digitized electrical signals into a first and a second band split digitized electrical signals, respectively. The invention also provides a system and a method for measuring the occlusion effect