Hearing Aid Transient Detection Upstream of the Filter Bank
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Solution Overview
Problem
Current hearing aids struggle to effectively manage transient noises, often causing discomfort due to their complex and power-consuming transient detection systems, which can introduce clicks and artifacts into the sound output, and fail to adequately differentiate between speech and non-speech transients.
Innovation Solution
A hearing aid with a transient detection system placed upstream of the filter bank, utilizing a slope detector to identify transients with a slope exceeding 5 dB/sample, and employing a 90% percentile estimator to control gain compression, allowing for faster response to transient signals without affecting speech quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a transient detection system is implemented in hearing aids to attenuate transient noises, then comfort from loud noises is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent extracts the transient detection function from the complex signal processing chain by placing a simple slope detector upstream of the filter bank. This early detection approach isolates the transient detection mechanism from the sophisticated multi-band processing, reducing overall system complexity while maintaining effective transient attenuation capability.
Solution Approach 2:
The patent segments the signal processing into distinct stages: a simple slope-based transient detector operates on the full-band signal upstream, while separate band-specific processing handles speech quality optimization downstream. This segmentation allows each component to be optimized independently, reducing overall complexity.
2Object-affected harmful factors
If complex transient detection systems are used to identify and attenuate transients, then transient noise comfort is improved, but artifacts and clicks are introduced into sound output
Solution Approach 1:
The patent changes the detection parameter from complex multi-feature analysis to a simple slope threshold (5 dB/sample). This parameter simplification reduces false detections and eliminates the generation of clicks and artifacts while maintaining effective transient attenuation. The slope-based approach provides smooth gain transitions without abrupt changes.
3Object-affected harmful factors
If transient attenuation is applied aggressively to reduce discomfort, then transient noise comfort is improved, but speech quality is degraded
Solution Approach 1:
The patent applies local quality by using the simple slope detector upstream to identify transients globally, then allowing subsequent band-specific processing to optimize speech quality locally in each frequency channel. This hierarchical approach ensures transient attenuation is applied uniformly while speech processing can be optimized independently for each band.
4Reliability
If slow attack-time is used in compression to avoid excessive gain reduction, then speech quality is maintained, but transient attenuation response is too slow
Solution Approach 1:
The patent performs preliminary action by detecting transients upstream of the filter bank before band-specific processing occurs. This early detection allows the system to prepare for rapid gain reduction in response to transients while maintaining normal compression settings for speech, thus achieving both fast transient response and speech quality preservation.
5Reliability
If slow release-time is used in compression to avoid excessive gain reduction, then speech quality is maintained, but gain recovery is too slow affecting soft sounds following loud sounds
Solution Approach 1:
The patent implements dynamic control by using the slope detector to dynamically adjust compression parameters based on transient detection. When transients are detected, the system rapidly reduces gain and maintains suppression longer than conventional release times would allow, ensuring complete attenuation of repeated transients while recovering quickly enough to preserve speech quality in subsequent soft sounds.
Data Source
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AI summary
A hearing aid has means (15) for detecting fast transients in the input signal and means (16, 12, 13) for attenuating the detected transients prior to presenting the signal with the attenuated transients to a user. Detection is performed by measuring the peak difference of the signal upstream of a band split filter bank (11) and comparing the peak difference against at least one peak difference limit. Then, if a transient is detected, a state machine (20) analyzes the peak level and the absolute average level of the signal and engages a gain calculator (12) to follow either the peak level or the absolute average level of the input signal for at least the duration of the transient in order to attenuate the transient. The engagement of the gain calculator (12) is performed in each frequency band dependent of the detected transient. The invention further provides a method for detecting fast transients.