Directional Noise Reduction System for Hearing Devices
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Solution Overview
Problem
Existing sound capture devices face challenges in adaptively switching between directional and omni-directional modes based on the quality of directional benefit, leading to sub-optimal noise reduction and voice enhancement in varying acoustic environments.
Innovation Solution
A sound capture device equipped with a directional noise reduction system that adjusts its mode based on the estimated directional performance of microphones, using a beamformer unit with a target maintaining and target cancelling beamformer, and a mode controller to determine the optimal mode control signal, allowing for seamless transitions between directional and omni-directional modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a sound capture device uses a fixed directional mode, then noise reduction from a specific direction is improved, but adaptability to varying acoustic environments deteriorates
Solution Approach 1:
The patent implements dynamic switching between directional and omni-directional modes based on real-time acoustic environment analysis. The system continuously monitors the acoustic scene and adapts its beamforming characteristics accordingly, transitioning from a fixed directional pattern to a dynamic configuration that optimizes noise reduction while maintaining adaptability to changing environments.
Solution Approach 2:
The system changes operational parameters (beamforming mode) based on environmental conditions. By analyzing acoustic characteristics and adjusting the directional pattern parameters in real-time, the system optimizes noise reduction performance for different scenarios while maintaining versatility across varying acoustic environments.
2Adaptability or versatility
If a sound capture device switches between directional and omni-directional modes, then adaptability to acoustic environments is improved, but device complexity deteriorates
Solution Approach 1:
The patent employs feedback mechanisms where the system continuously monitors acoustic environment characteristics and uses this information to automatically determine the appropriate operating mode. The feedback loop analyzes environmental cues and triggers mode transitions, reducing the need for complex manual control while maintaining high adaptability to varying acoustic scenarios.
3Measurement precision
If a sound capture device uses directional processing, then signal-to-noise ratio for target direction is improved, but voice capture from all directions deteriorates
Solution Approach 1:
The system dynamically adjusts its beamforming characteristics based on the acoustic scene. When a dominant noise source is detected from a specific direction, the system activates directional processing to improve signal-to-noise ratio for targets in other directions. When the environment is acoustically benign or multiple speakers are present, the system transitions to omni-directional mode to capture voice from all directions, thus optimizing both SNR and omnidirectional capture capability.
Data Source
Figure 1A~1B
Figure 1C
Figure 2A~2D
AI summary
A hearing device configured to be worn by a user comprises a) an input unit providing a multitude of electric input signals, each comprising a target signal component and a noise signal component; b) an own voice detector configured to provide an own voice control signal indicative of whether or not, or with what probability, a given electric input signal, originates from the voice of the user. The own voice detector comprises b1) a beamformer unit comprising b1.1) a target maintaining, reference beamformer configured to leave signal components from a fixed target direction un-attenuated or less attenuated relative to signal components from other directions, and providing a current reference signal; and b1.2) a target cancelling beamformer configured to attenuate signal components from said target direction, whereas signal components from other directions are attenuated less relative to signal components from said target direction, and providing a current target cancelling signal. The fixed target direction is a direction from the hearing device towards the user's mouth and the target signal is the user's own voice. The own voice detector further comprises c) a controller for determining the own voice control signal in dependence of the current reference signal and the current target cancelling signal.