Earplug Vent and Variable Gain for Speech Intelligibility in Noise
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Solution Overview
Problem
Existing solutions fail to effectively enhance listening comfort and speech recognition in noisy environments, as they often introduce processing artefacts, unnatural sounds, and occlusion effects, while traditional hearing protectors and aids either attenuate too much or not enough, and struggle with handling the occlusion issue.
Innovation Solution
A speech intelligibility enhancing system that combines acoustically attenuating and electroacoustic paths to optimize sound pressure levels, reduce occlusion, and apply variable gains to improve phoneme discrimination, using a directional microphone and peak limiting mechanisms to manage noise exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional passive hearing protectors are used to attenuate noise, then noise exposure is reduced, but speech recognition deteriorates due to excessive attenuation especially at higher frequencies
Solution Approach 1:
The system dynamically adjusts the attenuation characteristics using an electroacoustic path with variable gain control. The attenuation is not fixed but adapts based on the acoustic environment and speech signals, allowing optimal noise reduction while preserving speech intelligibility across different listening conditions
Solution Approach 2:
The system applies different attenuation levels to different frequency bands and spatial locations. The electroacoustic path provides frequency-selective attenuation that is less aggressive at speech-critical frequencies compared to traditional passive protectors, while the directional microphone pattern provides spatially selective noise reduction
2Stability of the object's composition
If musicians ear-plugs are used to evenly attenuate across broad frequency range, then music perception is preserved, but speech understanding deteriorates due to excessive overall attenuation
Solution Approach 1:
The system changes the attenuation parameters dynamically based on the type of sound being processed. The electroacoustic path applies different gain settings for speech versus music, and the directional microphone pattern adjusts its characteristics based on the acoustic environment, providing optimal parameters for each sound type rather than a fixed attenuation curve
3Stress or pressure
If conventional hearing aids amplify sound to improve audibility, then speech audibility is improved, but speech recognition in noise deteriorates due to general amplification without selective processing
Solution Approach 1:
The system applies local quality enhancement by using a directional microphone pattern that provides spatially selective amplification. The electroacoustic path amplifies sounds from the direction of interest while attenuating noise from other directions, rather than providing uniform omnidirectional amplification
Solution Approach 2:
The electroacoustic path acts as an intermediary between the environment and the ear canal, providing selective signal processing. The system processes the acoustic signal electronically before delivery, allowing sophisticated noise reduction and speech enhancement algorithms to improve speech recognition in noisy environments
4Object-affected harmful factors
If acoustically attenuating path is used to reduce noise, then noise exposure is reduced, but occlusion effect increases due to blocking of ear canal
Solution Approach 1:
The vent acts as an intermediary acoustic pathway that bypasses the blocking effect of the earplug. By providing a dedicated acoustic channel for low-frequency sounds including own voice, the vent mediates between the occluding earplug and the ear canal, allowing natural voice perception while maintaining noise attenuation
Solution Approach 2:
The acoustic pathway is segmented into two separate routes: the blocked path through the earplug material for high-frequency noise attenuation, and the vent path for low-frequency sound transmission. This segmentation allows each path to be optimized for its specific function without compromising the other
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system enhances speech recognition in noisy environments by reducing occlusion, managing noise exposure, and maintaining natural sound frequency response, allowing users to stay longer in loud conditions without hearing damage.
Implementation Method 1
comprises a vent acoustically coupling the environment to the ear canal
Implementation Method 2
an acoustically attenuating path comprising a vent arranged to allow environmental sound to reach the tympanic membrane of the person, however at an attenuated level
Implementation Method 3
An electroacoustic path comprising a microphone, a preamplifier, a variable gain and a loudspeaker
Implementation Method 4
an electroacoustic path comprising a microphone, a preamplifier, a variable gain and a loudspeaker
Data Source
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AI summary
A speech intelligibility enhancing system for difficult acoustical conditions is disclosed, the speech intelligibility enhancing system comprising at least one ear plug (201) for insertion in an ear canal (218) of a person, the at least one ear plug being arranged with an ear canal facing portion (401) and an environment facing portion (402), and the at least one ear plug comprising an acoustically attenuating path (214; 214, 213) comprising a vent (214) coupling said environment facing portion (402) with said ear canal facing portion (401); and an electroacoustic path (202, 204, 209; 202, 203, 204, 208, 209, 210, 211, 212) comprising a microphone (202) at said environment facing portion (402), a variable gain (204) and a loudspeaker (209) at said ear canal facing portion (401); wherein said acoustically attenuating path (214; 214, 213) is arranged with a transfer function from said environment facing portion (402) to said ear canal facing portion (401) having a low pass characteristic having a low pass cut¬ off frequency and said low pass characteristic attenuating sound by a nominal attenuation (Go) for frequencies below said cut-off frequency.