Reduction of the occlusion effect induced by earplugs using quasi perfect broadband absorption

Type de document

Études primaires

Année de publication

2022

Langue

Anglais

Titre de la revue

Scientific Reports

Résumé

Passive earplugs are used to prevent workers from noise-induced hearing loss. However, earplugs often induce an acoustic discomfort known as the occlusion effect. This phenomenon corresponds to an increased auditory perception of the bone-conducted part of physiological noises at low-frequency and is associated with the augmentation of the acoustic pressure in the occluded earcanal. In this work, we report a new concept of passive earplugs for mitigating the occlusion effect between 100 Hz and 1 kHz. The strategy consists in reducing the input impedance of the earplug seen from the earcanal by using quasi-perfect broadband absorbers derived from the field of meta-materials. The proposed “meta-earplug” is made of 4 critically coupled Helmholtz resonators arranged in parallel. Their geometry is optimized using an evolutionary algorithm associated with a theoretical model of the meta-earplug input impedance. The latter is validated against a finite-element approach and impedance sensor measurements. The meta-earplug is manufactured by 3D printing. Artificial test fixtures are used to assess the occlusion effect and the insertion loss. Results show that the meta-earplug induces an occlusion effect approximately 10 dB lower than foam and silicone earplugs while it provides an insertion loss similar to the silicone earplug up to 5 kHz.

Mots-clés

Protection de l'ouïe, Hearing protection, Propagation du son, Sound propagation, Protège-tympan, Earplug, Atténuation du bruit, Sound attenuation, Évaluation du confort, Comfort assessment

Numéro de projet IRSST

n/a

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