Binaural Hearing Aid Spatial Hearing Coherence Mixing
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Solution Overview
Problem
Current binaural beamformers struggle to effectively reduce noise while preserving binaural cues in dynamic acoustic environments, often distorting residual noise cues and impacting spatial hearing perception, especially when noise reduction methods require unavailable real-time statistics or assume static noise conditions.
Innovation Solution
A method for a binaural hearing aid that generates binaural beamformer signals by deriving coherence parameters from reference and supplementary input signals, allowing for local mixing to restore binaural cues through frequency-dependent adjustments, preserving spatial perception and noise reduction across various acoustic environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If binaural beamforming is applied to reduce noise, then noise reduction is improved, but binaural cues of residual noise are distorted
Solution Approach 1:
The patent segments the signal processing into multiple stages: first generating a binaural beamformer signal for noise reduction, then separately analyzing coherence between reference and beamformer signals to determine mixing parameters, and finally combining both signals with appropriate weighting. This segmentation allows independent optimization of noise reduction and binaural cue preservation
Solution Approach 2:
The patent dynamically changes the mixing parameter based on coherence measurements and signal-to-noise ratio estimates. By adjusting the mixing parameter α(f,t) in the range [0,1] according to real-time acoustic conditions, the system adapts the balance between noise reduction and binaural cue preservation, achieving both goals under different operating conditions
2Loss of information
If common gain is applied to preserve binaural cues of noise, then binaural cues are preserved, but noise reduction is significantly reduced
Solution Approach 1:
The patent transitions from static common gain application to dynamic mixing parameter adjustment. The mixing parameter α(f,t) is continuously adapted based on coherence measurements and SNR estimates, allowing the system to switch between noise reduction mode (α close to 0) and cue preservation mode (α close to 1) depending on real-time acoustic conditions
Solution Approach 2:
The patent implements feedback by measuring coherence between reference signals and binaural beamformer signals, estimating SNR, and using these measurements to adjust the mixing parameter. This closed-loop control enables the system to automatically optimize the balance between noise reduction and binaural cue preservation based on actual acoustic environment
3Object-affected harmful factors
If multi-channel Wiener filter is used for noise reduction, then noise reduction is improved, but real-time statistics are required which are not available
Solution Approach 1:
The patent makes the system self-sufficient by estimating SNR and coherence directly from the available microphone signals without requiring external statistics or training data. The coherence between reference and beamformer signals, along with power spectral density estimates, provide all necessary information for adaptive mixing parameter calculation, eliminating dependency on unavailable real-time statistics
4Object-affected harmful factors
If interaural transfer functions are assumed for noise reduction, then noise reduction is improved, but dynamic acoustic environments make this assumption invalid
Solution Approach 1:
The patent replaces static assumptions about interaural transfer functions with dynamic coherence measurements. By continuously measuring coherence between reference signals and binaural beamformer signals in real-time, the system adapts to changing acoustic environments including moving noise sources and varying room acoustics, maintaining effectiveness where fixed transfer function assumptions fail
Data Source
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AI summary
The invention proposes a method for improving the spatial hearing perception of a binaural hearing aid (20), said binaural hearing aid (20) comprising a first local unit (21) and a second local unit (22), wherein in the first local unit (21), a first input signal (26) is generated from an environment sound (25) by a first input transducer (24), and a first reference signal (32) is derived from the first input signal (26), wherein in the second local unit (22), a second input signal (30) is generated from the environment sound (25) by a second input transducer (28), and a second reference signal (34) is derived from the second input signal (30), wherein from the first reference signal (32) and the second reference signal (34), a first binaural beamformer signal (36) is derived, wherein from the first reference signal (32) and the first binaural beamformer signal (36), a first coherence parameter (38) is derived, wherein from the first coherence parameter (38), a first mixing parameter (40) is derived, and wherein the first reference signal (32) and the first binaural beamformer signal (36) are mixed by means of the first mixing parameter (40) in order to generate a first output signal (42).