Hearing Aid Gain Limiting via Multi-Microphone Feedback Estimation
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Solution Overview
Problem
Existing hearing aids with multiple microphones face challenges in determining the maximum gain limit without introducing acoustic feedback or artifacts, particularly in systems with feedback paths, which can affect directional processing and overall system complexity.
Innovation Solution
A hearing aid system that uses multiple microphones to estimate acoustic feedback signals and interpolates the maximum gain limit based on the mixing ratio of these signals, allowing for directional processing and feedback compensation while maintaining a low system complexity by deriving the gain limit from the estimated feedback signals and mixing ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple microphones are used with feedback paths, then directional processing capability is improved, but acoustic feedback and artifacts appear due to insufficient gain limitation
Solution Approach 1:
The system performs preliminary estimation of acoustic feedback signals from each microphone branch before directional processing. By anticipating the feedback signals and calculating maximum gain limits in advance based on these estimates, the system prevents acoustic feedback artifacts from occurring during directional processing, thus resolving the contradiction between enhanced directional capability and feedback suppression.
Solution Approach 2:
The system implements a feedback mechanism where estimated feedback signals from each microphone are used to dynamically adjust the maximum gain limit. This feedback loop ensures that the gain applied in directional processing does not exceed the calculated limit, thereby preventing acoustic feedback while maintaining the directional processing capability provided by multiple microphones.
2Object-affected harmful factors
If independent feedback compensation is applied to each microphone signal, then feedback reduction is improved, but system complexity and processing load increase
Solution Approach 1:
The system merges the feedback compensation process into the overall directional processing framework rather than treating each microphone independently. By combining the estimation of feedback signals from multiple microphones and calculating a unified maximum gain limit based on the mixing ratio, the system reduces processing complexity while still effectively reducing feedback signals from all microphone branches.
Solution Approach 2:
The system implements a universal feedback compensation approach that handles multiple microphone signals through a single gain limitation mechanism. The maximum gain limit calculation serves multiple functions: it prevents feedback in each individual microphone branch while also maintaining the integrity of the directional processing, thus reducing overall system complexity compared to separate compensation schemes.
3Reliability
If maximum gain limit is set conservatively, then acoustic feedback is prevented, but hearing loss compensation effectiveness is reduced
Solution Approach 1:
The system dynamically adjusts the maximum gain limit based on the estimated feedback signals and the current mixing ratio of microphone inputs. Rather than using a fixed conservative limit, the gain limit adapts in real-time to the acoustic environment and directional processing requirements, thereby maintaining feedback stability while maximizing hearing loss compensation effectiveness under varying conditions.
Solution Approach 2:
The system changes the gain limit parameter dynamically based on the mixing ratio and estimated feedback characteristics. By adjusting this parameter according to the specific operational conditions and directional processing configuration, the system achieves optimal balance between preventing acoustic feedback and providing effective hearing loss compensation, rather than relying on a static conservative setting.
Data Source
AI summary
A hearing aid (200) with multiple microphones comprises a first microphone (1) for converting sound into a first audio signal, a second microphone (20) for converting sound into a second audio signal, directional processing means for combining the first and said second audio signal according to a mixing ratio to form a spatial signal, estimating means for estimating a first acoustic feedback signal entering the first microphone and a second acoustic feedback signal entering the second microphone, processing means (4) for processing said spatial signal by applying a gain not exceeding a resulting maximum gain limit to form a hearing loss compensation signal, wherein the resulting maximum gain limit is derived from the first and second acoustic feedback signals and the mixing ratio, and an output transducer (3) for converting the hearing loss compensation signal into an acoustic output. The invention further provides a method and a computer program product.