Hearing Device Own-Voice Detection Using Ear Canal Microphone Filtering
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Solution Overview
Problem
Current methods for detecting a hearing device user's own voice activity are unreliable and complex, leading to issues like loud or unnatural voice perception, especially when the ear canal is sealed.
Innovation Solution
A method using an ambient microphone, an ear canal microphone, and a signal processing unit to filter and compare audio signals, detecting own-voice presence by computing a difference between internal and filtered audio signals, and controlling active occlusion based on this detection to mitigate the occlusion effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If methods based on single microphone signal measures (overall level, pitch, spectral shape) are used for own-voice detection, then the device complexity is low, but the detection reliability is poor
Solution Approach 1:
The patent divides the sound field into distinct spatial zones using multiple microphones positioned at different locations (ambient microphone outside ear canal, ear canal microphone inside ear canal). This segmentation allows separate analysis of sound sources based on their spatial origin, improving detection reliability by comparing signals from different spatial segments rather than relying on single complex features.
Solution Approach 2:
The patent introduces an intermediary approach by using the transfer function as a mediator to model and predict the relationship between receiver output and ear canal microphone signal. This transfer function acts as a bridge that allows the system to separate own-voice components from other sounds through predictive modeling, achieving reliable detection without requiring overly complex real-time analysis.
2Reliability
If complex signal analysis methods (direct-to-reverberant ratio assessment) are used for own-voice detection, then the detection reliability is high, but the device complexity increases
Solution Approach 1:
The patent segments the audio signal into distinct components based on spatial origin: ambient sound captured by the ambient microphone, ear canal internal sound captured by the ear canal microphone, and receiver-generated sound. This segmentation simplifies the analysis by allowing direct comparison of separated signal components rather than requiring complex decomposition of mixed signals.
Solution Approach 2:
The patent employs feedback mechanisms where the transfer function is determined through measurement and then used to predict and cancel receiver-generated components in real-time. This feedback loop allows the system to continuously refine its own-voice detection by comparing actual ear canal microphone signals with predicted signals, achieving high reliability through iterative refinement rather than single-pass complex analysis.
3Object-affected harmful factors
If active occlusion control is continuously activated to mitigate occlusion effect, then the sound quality improves, but the power consumption increases
Solution Approach 1:
The patent makes the active occlusion control dynamic by continuously monitoring own-voice detection results and adjusting the control state accordingly. The system transitions between active and inactive states based on real-time detection of user speech, allowing the occlusion mitigation to be applied only when necessary (during user speech) rather than continuously, thereby reducing power consumption while maintaining sound quality when needed.
Data Source
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AI summary
The present invention proposes a method for operating a hearing device comprising an ambient microphone (1), a signal processing unit (2), a receiver (3) and an ear canal microphone (4), the method being characterised by the steps of filtering the audio signal processed by the signal processing unit (1.) with a filter (7) having a transfer function at least comprising a transfer function from an output of the receiver (3) to an input of the ear canal microphone (4) when the hearing device is turned on and being worn in an ear canal of the user, computing a difference between the audio signal picked up by the ear canal microphone (4) and the filtered signal, and detecting a presence of own-voice of the user based on the difference. Furthermore, a hearing device including an own-voice detection unit (5) is provided, which is adapted to perform the proposed method.