Adaptive Level Estimation for Binaural Hearing Compression
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Solution Overview
Problem
Existing audio processing devices, such as hearing aids, face challenges in accurately estimating sound levels across multiple frequency bands, leading to issues like decreased speech intelligibility due to stationary noise masking low-level signal content, especially when using a limited number of frequency bands for compression.
Innovation Solution
The proposed solution involves a hybrid level estimation approach using a high-resolution level estimator in many frequency bands for slowly varying signals and a low-resolution estimator in few frequency bands for fast varying signals, with a fading scheme to combine the estimates, ensuring proper sound perception and intelligibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a limited number of frequency bands are used for compression, then device complexity is reduced, but measurement precision of sound levels decreases
Solution Approach 1:
The patent divides the frequency spectrum into multiple bands and applies different compression strategies to different bands. Specifically, it uses a multi-band compression architecture where each band can be independently processed, allowing the system to achieve high measurement precision in critical frequency regions while maintaining overall device complexity at acceptable levels through selective processing.
Solution Approach 2:
The patent implements local quality by applying different compression parameters and processing depths to different frequency bands based on their importance. Critical frequency bands containing speech information receive more precise processing with smaller bandwidth, while less critical bands use coarser processing, thereby optimizing the balance between measurement precision and device complexity locally in each frequency region.
2Speed
If fast acting level estimators are used, then response speed to signal changes is improved, but measurement precision of steady-state levels deteriorates
Solution Approach 1:
The patent employs dynamic adaptation of compression parameters based on the temporal characteristics of the input signal. The system automatically adjusts between fast and slow acting level estimators depending on whether the signal is stationary or changing rapidly, allowing optimal response speed and measurement precision to be maintained under different operating conditions through real-time parameter adaptation.
Solution Approach 2:
The patent uses a dual-path architecture where a fast acting level estimator provides immediate response to signal changes by skipping detailed analysis during transient periods, while a slow acting estimator provides precise steady-state measurements. The system intelligently selects which path to use based on signal characteristics, allowing fast response when needed without sacrificing steady-state accuracy when the signal is stable.
Data Source
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AI summary
An adaptive level estimator for providing a level estimate of an electric input signal representing sound is provided. The adaptive level estimator comprises • a first level estimator configured to provide a first level estimate of the electric input signal in a first number K1 of frequency bands; • a second level estimator configured to provide a second level estimate of the electric input signal and/or associated attack/release time constants in a second number K2 of frequency bands, wherein K2 is smaller than K1; and • a level control unit receiving said first and second level estimates and configured to provide said resulting level estimate based on said first and said second level estimates and/or said associated attack/release time constants. The invention may e.g. be used in devices or applications that benefit from a dynamic adaptation of an input signal level to a listener's (possibly limited) dynamic range of sound level perception, or to any other specific dynamic range deviating from that of the environment sound.