Audio Signal Compression Using Masking Curves for Hearing Loss
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Solution Overview
Problem
Conventional hearing aid processing methods, relying on linear filtering techniques, are inadequate for providing an enhanced audio experience for hearing-impaired individuals, especially when consuming audio content with limited dynamic range, as they fail to accurately simulate the sound perception of individuals with normal hearing.
Innovation Solution
A method that involves deriving a user's hearing profile through masking contour curve analysis, allowing for the customization of audio signals to match their specific hearing abilities by parameterizing a digital compression system to enhance audio perception, using both demographic data and hearing test results to create a target masking contour curve for multi-band compression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If linear filtering techniques (equalization) are used to compensate for hearing loss, then frequency gain can be adjusted according to user's hearing profile, but the method is only applicable to conductive hearing loss and cannot accurately model sensorineural hearing loss
Solution Approach 1:
The patent changes the fundamental parameter of the processing approach from linear filtering to non-linear processing. Specifically, it uses masking contour curves and signal-to-noise ratio manipulation to transform the audio signal in a non-linear manner that accurately reflects the complex physiology of sensorineural hearing loss, thereby achieving both versatility across hearing loss types and reliability in modeling
Solution Approach 2:
The patent substitutes the mechanical linear filtering approach with a psychoacoustic-based non-linear processing system. Instead of simply boosting frequencies, it replaces the mechanical EQ approach with a system that simulates the human auditory system's non-linear response to sound, including masking effects and dynamic range compression
2Manufacturing precision
If conventional hearing aid processing (wide dynamic range compression) is applied to recorded audio content, then faint sounds can be amplified, but the processing degrades the perceived quality of audio content with already limited dynamic range
Solution Approach 1:
The patent applies partial compression only to frequency regions where masking occurs, rather than applying wide dynamic range compression across the entire audio spectrum. By selectively compressing only the problematic frequency bands identified through masking contour analysis, it provides benefit to faint sounds while preserving the quality of the overall audio content
Solution Approach 2:
The patent applies different processing characteristics to different frequency bands based on the user's specific hearing profile and masking contours. Instead of uniform compression across all frequencies, it tailors the compression ratio and threshold locally to each frequency band, thereby improving faint sound detection in affected bands while maintaining audio quality in unaffected bands
3Measurement precision
If linear equalization is used to boost frequencies for hearing loss compensation, then frequency response can be corrected, but the human auditory system's non-linear response is not accounted for
Solution Approach 1:
The patent fundamentally changes the processing parameter from static linear gain to dynamic non-linear transformation. It uses masking contour curves to determine frequency-dependent compression ratios, transforming the audio signal in a manner that reflects the non-linear physiology of the human auditory system rather than applying simple linear frequency boosting
4Ease of manufacture
If simple equalization techniques are applied, then the processing is computationally simple, but the method cannot provide beneficial sound personalization for sensorineural hearing loss
Solution Approach 1:
The patent performs preliminary analysis to obtain the user's masking contour curve and hearing profile before applying the compression processing. By pre-characterizing the user's specific hearing loss pattern and masking behavior, the system can then apply targeted non-linear processing that is both computationally efficient and highly effective for that individual's type of hearing loss
Data Source
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AI summary
A method of enhancing an audio signal from an audio output device is provided. For a frequency band, a user masking contour curve covering at least a part of said frequency band is obtained, a target masking contour curve is derived from the user masking contour curve, and a multi-band digital compression system is parameterized based on the sound level of the target masking contour curve at a given frequency and the sound level of the user masking contour curve at the same given frequency. The obtained parameters are outputted to provide an enhanced audio signal.