Adaptive Beamformer Steering for Off-Axis Speech Detection
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Solution Overview
Problem
Hearing aids struggle to distinguish speech from environmental noise, leading to difficulty in understanding speech in noisy environments, as simple amplification does not effectively address the loss of frequency resolution due to damaged outer hair cells, and existing adaptive beamforming algorithms either reduce both noise and speech or require discrete mode changes that can be annoying.
Innovation Solution
A hearing assistance system with an adaptive directionality controller that includes a beamformer, a speech detector, and a steering module to detect off-axis speech and adjust the beamformer's directionality without changing noise levels significantly, allowing for continuous speech intelligibility without audible mode changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adaptive beamforming is used to enhance speech from target direction, then speech intelligibility is improved, but off-axis speech is canceled which reduces communication flexibility
Solution Approach 1:
The beamformer dynamically adjusts its steering vector based on real-time detection of off-axis speech. When off-axis speech is detected, the system steers the beamformer away from that direction, allowing the user to hear both the target direction speech and the off-axis speech speaker, thus resolving the contradiction between speech intelligibility and communication flexibility
Solution Approach 2:
The system continuously monitors the acoustic environment for off-axis speech and uses this feedback to adaptively steer the beamformer. This closed-loop control enables the system to maintain optimal speech intelligibility while responding to communication needs, allowing flexible interaction with multiple speakers
2Reliability
If beamformer steers to enhance target direction speech, then speech intelligibility is improved, but noise levels may change which affects listening comfort
Solution Approach 1:
The system changes the beamformer steering parameters dynamically based on the detected acoustic scene. By adjusting the steering vector angles and weights in response to off-axis speech detection, the system maintains speech intelligibility while minimizing unwanted noise level changes that would affect listening comfort
3Device complexity
If discrete mode changes are used in beamforming, then speech processing is simplified, but audible mode changes occur which are annoying to users
Solution Approach 1:
Instead of discrete mode changes, the system uses continuous dynamic steering of the beamformer. The steering vector is continuously adjusted based on real-time off-axis speech detection, providing smooth transitions that are imperceptible to users while maintaining simplified processing through a single continuous control mechanism
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
The system effectively reduces cancellation of off-axis speech, maintaining speech intelligibility while minimizing noise level changes, thus improving understanding of speech in noisy environments without the annoyance of frequent mode changes.
Implementation Method 1
The beamformer cancels received sounds that are not from the target direction by beamforming
Data Source
AI summary
A hearing assistance system includes an adaptive directionality controller to control a target direction for sound reception. The adaptive directionality controller includes a beamformer, a speech detector to detect off-axis speech being speech that is not from the target direction, and a steering module to steer the beamformer in response to a detection of the off-axis speech.