Multiband Hearing Protection Limiter for Speech Intelligibility
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Solution Overview
Problem
Hearing protection devices struggle to limit sound pressure levels effectively while maintaining speech intelligibility, often resulting in excessive gain reductions that compromise communication in noisy environments.
Innovation Solution
A hearing protection device with a multiband limiter that divides incoming audio signals into sub-bands, estimates signal strength parameters, and applies gain reductions only where necessary, using a limiter controller to manage gain reductions based on signal strength thresholds, thereby limiting broadband output signal strength while preserving speech clarity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If gain reduction is applied to limit sound pressure levels, then hearing protection is improved, but speech intelligibility deteriorates due to excessive gain reductions
Solution Approach 1:
The audio signal is divided into multiple frequency bands, allowing independent gain reduction control for each band. This segmentation enables selective attenuation of harmful frequencies while preserving speech-containing bands, resolving the contradiction between hearing protection and speech intelligibility.
Solution Approach 2:
Different gain reduction levels are applied to different frequency bands based on their specific characteristics. Speech-containing bands maintain higher gain while noisy bands receive stronger attenuation, creating local quality differences that protect hearing without compromising communication.
2Object-affected harmful factors
If noise reduction is applied in noisy environments, then hearing protection is improved, but communication capability deteriorates
Solution Approach 1:
The gain reduction levels are dynamically adjusted based on real-time analysis of each frequency band's signal strength and noise characteristics. This dynamic adaptation allows the system to maintain communication capability when speech is present while providing protection when only noise is detected.
Solution Approach 2:
The system continuously monitors the output of each frequency band and adjusts gain reduction levels accordingly. This feedback mechanism ensures that communication capability is maintained by detecting speech signals and reducing attenuation in those bands while still protecting against harmful noise exposure.
Data Source
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AI summary
A hearing protection device and a method of operating a hearing protection device is disclosed. The hearing protection device comprises a first microphone for provision of a first microphone input signal; a sub-band splitting module for dividing the first microphone input signal into a plurality of sub-band signals, an estimator module for estimating a signal strength parameter of respective sub-band signals including a first signal strength parameter of a first sub-band signal and a second signal strength parameter of a second sub-band signal; a multiband limiter configured for applying a gain reduction to the first microphone input signal or each of the sub-band signals; and a limiter controller connected to the multiband limiter, wherein the limiter controller is configured to determine gain reductions for the sub-band signals of the first microphone input signal, wherein a second gain reduction for the second sub-band signal is based on the first signal strength parameter for the first sub-band signal, and wherein the limiter controller is configured to control the multiband limiter to apply the second gain reduction to the second sub-band signal .