Vented Earplug Acoustics 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, or exacerbate the occlusion effect, making it difficult for individuals with normal or near-normal hearing to understand conversations in challenging acoustical conditions.
Innovation Solution
A speech intelligibility enhancing system comprising ear plugs with an acoustically attenuating path and an electroacoustic path, featuring a low pass characteristic for sound attenuation and a variable gain system to optimize sound pressure levels, reduce occlusion, and improve speech recognition by applying a nominal attenuation and high pass gain, respectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional passive hearing protectors attenuate sound, then noise protection is improved, 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 that responds to environmental conditions and speech detection, allowing the attenuation to be optimized in real-time rather than being fixed passively
Solution Approach 2:
The system changes the attenuation parameters frequency-dependently, applying less attenuation to speech-relevant frequencies while maintaining protection at other frequencies, thereby preserving speech recognition while providing noise protection
2Loss of information
If hearing aids amplify sound to improve audibility, then speech intelligibility is improved, but occlusion effect worsens due to blocking of the ear canal
Solution Approach 1:
The system introduces an intermediary electroacoustic path that includes a microphone and loudspeaker to detect and reproduce speech signals, allowing the occlusion effect to be compensated without directly amplifying all sounds through the ear canal
Solution Approach 2:
The system applies different processing to different frequency regions, with the low-pass characteristic preserving bass frequencies for natural sound perception while allowing electroacoustic enhancement at higher frequencies where speech information resides
3Stability of the object's composition
If musicians ear-plugs evenly attenuate across broad frequencies, then music perception is preserved, but speech understanding deteriorates due to excessive overall attenuation
Solution Approach 1:
The system dynamically adjusts attenuation based on detected speech characteristics and environmental conditions, reducing attenuation when speech is detected rather than maintaining fixed even attenuation across all conditions
Solution Approach 2:
The system changes attenuation parameters based on frequency and environmental context, applying frequency-dependent attenuation that preserves speech intelligibility while maintaining music perception characteristics
4Object-generated harmful factors
If hearing aids provide vent for bone conducted sound, then occlusion effect is reduced, but attenuation of bass frequencies is prevented
Solution Approach 1:
The system uses the electroacoustic path with microphone and loudspeaker as an intermediary to detect and reproduce bass frequencies that would otherwise be blocked, allowing venting to reduce occlusion without sacrificing bass attenuation
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 significantly increases speech intelligibility in noisy environments by reducing noise exposure, minimizing the occlusion effect, and protecting against loud sounds, allowing users to stay longer in noisy situations while maintaining natural sound perception.
Implementation Method 1
an acoustically attenuating path comprising a vent coupling said environment facing portion with said ear canal facing portion; and arranged with a transfer function from said environment facing portion to said ear canal facing portion having a low pass characteristic having a low pass cut-off frequency and said low pass characteristic attenuating sound by a nominal attenuation for frequencies below said cut-off frequency
Implementation Method 2
an electroacoustic path comprising a microphone at said environment facing portion, a variable gain and a loudspeaker at said ear canal facing portion
Implementation Method 3
an electroacoustic path comprising a microphone at said environment facing portion, a variable gain and a loudspeaker at said ear canal facing portion
Data Source
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.