Bilateral Hearing Aid Temporal Decorrelation Beamforming
Solution Overview
Problem
Existing binaural hearing aid systems face challenges in providing flexible speech intelligibility improvement and mitigating the 'tunnel hearing' sensation in noisy environments by effectively managing off-axis acoustic signal sources, as they often result in reduced situational awareness due to high directivity index and narrow angular sensitivity ranges.
Innovation Solution
A binaural hearing aid system comprising two hearing aids with signal processors that generate monaural and bilateral beamforming signals, featuring adjustable polar patterns to enhance sensitivity towards the target direction while reducing sensitivity to off-axis sources, and incorporating time delays to reduce correlation between signals, thereby improving sound source segregation and situational awareness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If binaural beamforming with high directivity index is applied to improve speech intelligibility in noisy environments, then speech understanding is enhanced, but situational awareness is reduced due to narrow angular sensitivity range
Solution Approach 1:
The patent segments the audio signal processing into multiple independent beamforming channels, each with distinct polar patterns. The first channel processes signals with a narrow polar pattern for speech enhancement, while the second channel processes signals with a wide polar pattern for situational awareness. These segmented channels are then combined to provide both speech intelligibility and environmental awareness simultaneously.
Solution Approach 2:
The system dynamically adjusts the mixing ratio between the narrow beamforming signal and wide beamforming signal based on listening conditions. The signal processor can adaptively control the contribution of each channel to optimize both speech understanding and situational awareness in real-time, transitioning between different beamforming modes as needed.
2Reliability
If strong beamforming with narrow angular range is used to achieve speech intelligibility improvement, then signal to noise ratio is enhanced, but off-axis sound sources are suppressed causing tunnel hearing sensation
Solution Approach 1:
The patent introduces a second beamforming channel as an intermediary that captures off-axis sounds. This intermediate wide-polar-pattern signal serves as a mediator between the narrow beamforming signal and the final output, preserving environmental sounds that would otherwise be suppressed. The intermediary channel bridges the gap between speech enhancement and environmental awareness.
Solution Approach 2:
The final audio output is a composite signal combining two distinct beamforming channels with different polar patterns. Similar to composite materials in engineering, the system combines the strengths of narrow beamforming (speech enhancement) and wide beamforming (environmental awareness) to create a hybrid signal that provides both high signal-to-noise ratio and comprehensive spatial awareness.
Data Source
AI summary
A binaural hearing aid system includes first and second hearing aids. A first signal processor of the first hearing aid is configured to generate a first monaural beamforming signal based on microphone signal(s) supplied by a first microphone arrangement of the first hearing aid, the first monaural beamforming signal exhibiting a first polar pattern with maximum sensitivity in a target direction. The first signal processor is also configured to: generate a bilateral beamforming signal based on the first monaural beamforming signal and a second monaural beamforming signal from the second hearing aid; generate a third monaural beamforming signal based on the microphone signal(s) and exhibiting a third polar pattern with maximum sensitivity at the ipsilateral side of the first hearing aid; delay the third monaural beamforming signal; and combine the first bilateral beamforming signal and the time-delayed third monaural beamforming signal to form a first hybrid beamforming signal.