User-Specific Dynamic Range Compression for Wearable Audio
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Solution Overview
Problem
Hearing aids introduce distortions in audio signals due to 'attack & release' type compression, particularly in multiband processing, which is not tailored to individual user's dynamic hearing range.
Innovation Solution
A method for dynamic range compression in wearable audio devices, such as hearing aids, that adjusts the audio signal based on user-specific frequency band-specific compression control functions, using short time frames and user-specific audiograms to minimize distortions and ensure natural sound perception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiband compression is applied to adjust dynamic range, then the audio signal is compressed more effectively, but distortions are introduced due to attack & release type compression
Solution Approach 1:
The audio signal is divided into multiple frequency bands using spectral analysis, and each frequency band is processed independently with its own compression control function. This segmentation allows targeted compression for each band without introducing the attack/release distortions associated with conventional multiband compression.
Solution Approach 2:
The patent employs dynamic compression control functions that adapt to the audio signal in real-time, using short time frames (e.g., 10-50ms) to continuously adjust compression parameters. This dynamic approach eliminates the need for fixed attack and release times, thereby avoiding the associated distortions while maintaining effective dynamic range compression.
2Device complexity
If conventional compression control functions are used, then the compression process is simple, but the compression is not tailored to individual user's dynamic hearing range
Solution Approach 1:
The patent applies different compression control functions to different frequency bands, with each function tailored to the user's specific hearing characteristics in that band. This local quality approach allows customization for each frequency region based on the user's audiogram, improving adaptability without requiring a complete redesign of the compression system.
Solution Approach 2:
The system changes compression parameters (compression ratio, knee point, gain) based on the user's measured hearing thresholds across different frequencies. By adjusting these parameters dynamically according to the user's audiogram, the system achieves user-specific adaptation while maintaining a relatively simple compression architecture.
3Measurement precision
If long time frames are used for spectral analysis, then the frequency resolution is improved, but temporal distortions increase
Solution Approach 1:
The patent uses short time frames (10-50ms) that provide sufficient frequency resolution for effective compression while avoiding the temporal distortions associated with longer time frames. This partial action approach balances the competing requirements by using just enough temporal resolution to achieve adequate spectral analysis without excessive temporal smearing.
Data Source
AI summary
410- The disclosure relates to a method for compressing a dynamic range of an audio signal in a wearable audio device. The wearable audio device may for example be a hearing aid, or earphone having an in-car component, e.g. an earbud, for being inserted into a hearing canal of a user or over car headphone etc. The method comprises determining a frequency spectrum of the audio signal over a plurality of frequency bands. For each of the plurality of frequency bands a magnitude value of the frequency spectrum is determined. The magnitude values are adjusted according to a predetermined frequency band-specific compression control function. The frequency band-specific compression control functions are user-specific.