Direction-Dependent AGC Compression for Hearing Aids
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Solution Overview
Problem
Conventional hearing aids using beamformers often suppress sound signals from directions other than the intended focus, leading to poor perception of relevant sound sources due to strong directional emphasis.
Innovation Solution
Implementing an automatic gain control (AGC) with a direction-dependent compression scheme that selectively amplifies sound signals from a relevant direction while minimizing suppression of other directions, using a combination of microphones and a direction determination unit to identify and emphasize specific sound sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a beamformer is used to emphasize sound signals from a specific direction, then speech intelligibility from that direction is improved, but sound signals from other directions are strongly suppressed
Solution Approach 1:
The patent applies dynamics by making the compression scheme adaptive rather than fixed. The direction determination unit dynamically identifies the relevant direction, and the compression scheme is adjusted in real-time based on this identification. This allows the system to emphasize sound from the relevant direction while applying different compression characteristics to other directions, reducing the harsh suppression effect of traditional beamformers while maintaining speech intelligibility enhancement.
Solution Approach 2:
The patent changes parameters by using a compression scheme with direction-dependent parameters instead of a fixed beamforming pattern. The compression ratio, knee point, and attack/release times are adjusted as parameters based on the identified relevant direction. This parameter adaptation allows selective emphasis of relevant sound sources while preserving more information from other directions compared to traditional beamforming approaches.
2Ease of operation
If strong directional emphasis is applied to prioritize sound from one direction, then speech intelligibility is improved, but potentially relevant sound signals from other directions are suppressed
Solution Approach 1:
The patent applies segmentation by dividing the acoustic environment into different directional segments. The direction determination unit separates sound sources by direction, and the compression scheme is applied differently to each directional segment. This segmentation allows the system to prioritize the relevant direction for speech intelligibility while maintaining adaptability to process and preserve sound information from other directions, rather than applying uniform suppression.
Solution Approach 2:
The patent achieves multi-functionality by making the compression scheme universal rather than direction-specific like a beamformer. The same compression processing unit handles all directions, but with adaptive parameters based on the identified relevant direction. This universal approach allows the system to maintain speech intelligibility enhancement while preserving the ability to perceive potentially relevant sound signals from multiple directions, increasing adaptability.
Data Source
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AI summary
A method for operating a hearing aid (2) is described, wherein the hearing aid (2) generates an input signal (E) from sound signals of the environment, wherein the hearing aid (2) has a signal processing unit (4) configured to modify the input signal (E) and thereby generate an output signal (A), wherein the signal processing unit (4) for modifying the input signal (E) includes an automatic gain control (10) which includes a compressor (12) operable with a compression scheme (K), wherein the environment is divided into several directions, one of which is selected as a relevant direction (R) by means of a direction determination unit (14), wherein the input signal (E) is modified depending on the direction by operating the compressor (12) with a compression scheme (K) which is set depending on the relevant direction (R).so that sound signals from the relevant direction (R) are emphasized compared to sound signals from other directions. Furthermore, a suitable hearing aid (2) is specified.