École de technologie supérieure, Montréal, Quebec H3C 1K3, Canada.
Institut de recherche Robert-Sauvé en santé et en sécurité du travail, Montréal, Quebec H3A 3C2, Canada.
J Acoust Soc Am. 2021 Sep;150(3):2006. doi: 10.1121/10.0006209.
The use of earplugs is commonly associated with an increased perception of the bone-conducted part of one's own physiological noise. This phenomenon is referred to as occlusion effect and is most prominent at low frequencies. Several factors influence the occlusion effect, such as the ear anatomy; the bone-conducted stimulation; and the type of occlusion device and its fit, insertion depth, and material properties. The latter factor is of great interest to potentially reduce the occlusion effect of passive earplugs. This paper investigates the mechanism(s) of contribution of earplugs to the objective occlusion effect. A two-dimensional axi-symmetric finite element model of the outer ear is used and investigated in an electro-acoustic framework. Simulation results are shown to compare reasonably well with measurement data, which qualifies the model to study the influence of earplugs on the occlusion effect. Two mechanisms are highlighted: (i) a Poisson effect induced by the normal component of the earcanal wall vibration and (ii) a longitudinal motion caused by the tangential component of the earcanal wall vibration. By varying the geometry of the surrounding tissues, the spatial distribution of the earcanal wall vibration is shown to influence the contribution of the earplug to the occlusion effect.
耳塞的使用通常与对自身生理噪声骨导部分的感知增加有关。这种现象被称为封闭效应，在低频时最为明显。有几个因素会影响封闭效应，例如耳朵解剖结构、骨导刺激以及封闭装置的类型及其适配、插入深度和材料特性。后者是潜在降低被动耳塞封闭效应的重要因素。本文研究了耳塞对客观封闭效应的贡献机制。使用了外耳的二维轴对称有限元模型，并在电声框架内进行了研究。模拟结果与测量数据相当吻合，这使得模型能够研究耳塞对封闭效应的影响。突出了两种机制：（i）耳道口壁振动法向分量引起的泊松效应和（ii）耳道口壁振动切向分量引起的纵向运动。通过改变周围组织的几何形状，展示了耳道壁振动的空间分布会影响耳塞对封闭效应的贡献。
