Binaural Hearing Device Active Occlusion Cancellation
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Solution Overview
Problem
Conventional binaural hearing devices face issues with active occlusion cancellation, leading to distortion and noise due to high amplitude signals exceeding the dynamic range of components, and binaural artefacts such as noise moving between ears and perceived differences in voice tone.
Innovation Solution
A binaural hearing device system that includes a method for binaural cancellation of undesired signals, involving the conversion of external and internal sound signals, processing to determine signal levels, and combining these signals to prevent exceeding the dynamic range, while using a binaural excessive level detector to adjust processing and attenuate signals as needed to avoid distortion and artefacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If active occlusion cancellation is implemented using high amplitude signals, then occlusion effect is reduced, but distortion and noise increase due to exceeding dynamic range
Solution Approach 1:
The system dynamically adjusts the amplitude of cancellation signals based on real-time detection of signal levels. The binaural excessive level detector monitors the amplitude of body conducted sound signals and dynamically scales the cancellation signals to prevent exceeding the dynamic range of audio components, thereby eliminating distortion and noise while maintaining occlusion cancellation effectiveness.
Solution Approach 2:
The system changes the amplitude parameter of cancellation signals adaptively. When body conducted sound signals exceed a threshold level, the system reduces the amplitude of the generated cancellation signals proportionally, ensuring that the sum of original and cancellation signals remains within the linear operating range of the audio components, thus preventing distortion.
2Object-affected harmful factors
If binaural active occlusion cancellation is implemented, then occlusion effect is reduced, but binaural artefacts occur such as noise moving between ears
Solution Approach 1:
The system merges the occlusion cancellation processing into a unified binaural framework. The binaural excessive level detector simultaneously monitors both ears and coordinates the cancellation signal generation across both channels, ensuring consistent amplitude scaling and synchronized processing. This unified approach prevents the generation of binaural artefacts such as noise moving between ears and perceived voice tone differences.
3Reliability
If signal amplitude is increased to improve cancellation effectiveness, then occlusion cancellation performance improves, but components exceed their dynamic range
Solution Approach 1:
The system employs feedback control through the binaural excessive level detector that continuously monitors the amplitude of body conducted sound signals and the generated cancellation signals. When the detector identifies that signal levels approach the dynamic range limits of audio components, it provides feedback to scale down the cancellation signal amplitude, ensuring optimal cancellation performance without exceeding component capabilities.
Data Source
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AI summary
A binaural hearing device system (1) is provided, comprising a binaural hearing device (10) with a first hearing device (10A) and a second hearing device (10B), each of which comprises an input transducer (12A, 12B) for provision of an input transducer audio signal (14A, 14B), a transducer audio signal processor (16A, 16B) configured for processing the input transducer audio signal (14A, 14B) into a processed transducer audio signal (22A, 22B), an ear canal microphone (28A, 28B) for provision of an ear canal microphone audio signal (30A, 30B) in response to sound received inside the ear canal of a user wearing the binaural hearing device (10), an ear canal audio signal processor (36A, 36B) configured for processing the ear canal microphone audio signal (30A, 30B) into a processed ear canal audio signal (38A, 38B), a first signal combiner (24A, 24B) configured for combining the processed input transducer audio signal (22A, 22B) with the processed ear canal audio signal (38A, 38B) into an output transducer audio signal (40A, 40B), e.g. for active occlusion cancellation, a signal level detector (58A, 58B) for determining a signal level of an audio signal selected from the group consisting of the output transducer audio signal (40A, 40B) and an audio signal included in formation of the output transducer audio signal (40A, 40B) and providing an output signal (62A, 62B) with the determined signal level, and an output transducer (44A, 44B) configured for converting the output transducer audio signal (40A, 40B) into an acoustic sound signal for emission towards an eardrum of the user, and wherein the binaural hearing device system (1) further comprises a binaural excessive level detector (60A, 60B) connected to the signal level detector (58A) of the first hearing device (10A) and the signal level detector (58B) of the second hearing device (10B) for reception of the output signals (62A, 62B) with the determined signal levels, and configured for outputting a first control signal (64A) to the ear canal audio signal processor (36A) of the first hearing device (10A) and a second control signal (64B) to the ear canal audio signal processor (36B) of the second hearing device (10B) in response to the determined signal levels, and wherein the ear canal audio signal processor (36A, 36B) in each of the first and second hearing devices (10A, 10B) is configured for processing the respective ear canal microphone audio signal (30A, 30B) in response to the respective one of the first and second control signals (64A, 64B) of the binaural excessive level detector (60A, 60B).