Acoustic Shock Detection in Hearing Devices
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Solution Overview
Problem
Existing methods for detecting acoustic shock signals in audio signals, particularly in hearing devices, face challenges such as delayed detection, distortion, and high computational requirements, which can lead to noticeable latency and loss of environmental awareness.
Innovation Solution
A method that monitors audio signals in the time-domain to detect the signal floor, peak level, attack time, and duration, calculating a shock contrast level and index, and applies adaptive gain reduction to manage acoustic shocks with zero time delay, suitable for low-power devices like hearing aids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sub-band shock detection is used, then shock detection accuracy is improved, but processing time and computational complexity increase causing noticeable latency
Solution Approach 1:
The patent divides the frequency spectrum into multiple sub-bands and performs shock detection independently in each sub-band. This segmentation allows the system to detect shocks with high accuracy across different frequency ranges while maintaining computational efficiency by processing each sub-band separately rather than analyzing the entire frequency spectrum at once.
Solution Approach 2:
The patent performs preliminary shock detection in the time domain before conducting detailed frequency domain analysis. By detecting potential shocks early using simple time-domain metrics (peak levels, attack times), the system can prepare for frequency-domain processing in advance, reducing the overall processing time and latency when actual shocks occur.
2Speed
If peak-clipping in time-domain is applied, then shock detection speed is improved, but sound quality distortion increases
Solution Approach 1:
The patent applies different processing strategies to different frequency sub-bands based on local characteristics. Instead of uniformly clipping peaks across the entire signal, the system identifies shock events in specific sub-bands and applies gain reduction only to those affected sub-bands, preserving sound quality in unaffected frequency ranges while still providing fast shock detection and response.
Solution Approach 2:
The patent uses feedback from time-domain shock detection to control frequency-domain processing. The time-domain detector provides real-time feedback about shock events, which triggers appropriate gain reduction in the frequency domain. This feedback mechanism enables fast response to shocks while avoiding unnecessary distortion in non-shock periods, maintaining overall sound quality.
3Reliability
If additional time delay is introduced for shock detection, then detection reliability is improved, but acoustic latency increases making shocks noticeable to users
Solution Approach 1:
The patent performs preliminary shock detection in the time domain using simple, fast metrics before the signal undergoes lengthy frequency-domain processing. This preliminary detection happens in advance and provides early warning of shock events, allowing the system to prepare for frequency-domain analysis without adding significant latency. The preliminary action ensures reliable detection while minimizing the time delay before user-perceptible processing begins.
Solution Approach 2:
The patent maintains continuous shock monitoring in the time domain throughout the frequency-domain processing pipeline. Rather than pausing for batch processing, the system continuously detects shocks using time-domain metrics while simultaneously performing frequency-domain analysis. This continuous useful action ensures that no shock goes undetected and maintains low latency by overlapping detection and processing operations.
Data Source
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AI summary
The present invention provides a method for detecting acoustic shock in an audio input signal (s(t)), comprising the steps of monitoring the input signal (s(t) ) in the time-domain. Thereby detecting the signal floor (Sn), detecting the peak level of the input signal (L) , detecting the attack time of the input signal (tl-t0), detecting the duration of the input signal (T). Based on those detections, determining a shock contrast level (SCL) as difference between the peak level (L) and the signal floor (Sn), determining a shock index (SI) by use of a shock index normalization constant ( s ) and comparing the shock contrast level (SCL) and the shock index (SI) with respective thresholds and indicating an acoustic shock if one or both thresholds are exceeded. Thus, the present method provides a quick and reliable shock detector that operates in the time-domain. The shock detection takes place with zero time delay, or even predicts the shock before it fully goes through the signal processing.