Department of Occupational and Environmental Medicine, Epidemiology and Hygiene, Istituto Nazionale Assicurazione Infortuni sul Lavoro-National Research Centre for Safety and Prevention at Workplace, Monteporzio Catone (Rome), Italy.
Caruso Department of Otolaryngology, University of Southern California, Los Angeles, California, USA.
J Acoust Soc Am. 2023 Jan;153(1):77. doi: 10.1121/10.0016809.
This study uses a 3-D representation of the cochlear fluid to extend the results of a recent paper [Sisto, Belardinelli, and Moleti (2021b). J. Acoust. Soc. Am. 150, 4283-4296] in which two hydrodynamic effects, pressure focusing and viscous damping of the BM motion, both associated with the sharp increase in the wavenumber in the peak region, were analyzed for a 2-D fluid, coupled to a standard 1-D transmission-line WKB approach to cochlear modeling. The propagation equation is obtained from a 3-D fluid volume conservation equation, yielding the focusing effect, and the effect of viscosity is represented as a correction to the local 1-D admittance. In particular, pressure focusing amplifies the BM response without modifying the peak admittance, and viscous damping determines the position of the response peak counteracting focusing, as sharp gradients of the velocity field develop. The full 3-D WKB formalism is necessary to represent satisfactorily the behavior of the fluid velocity field near the BM-fluid interface, strictly related to viscous losses. As in finite element models, a thin layer of fluid is effectively attached to the BM due to viscosity, and the viscous force associated with the vertical gradient of the fluid vertical velocity acts on the BM through this layer.
本研究使用耳蜗液的三维表示来扩展最近一篇论文[Sisto、Belardinelli 和 Moleti（2021b）。J. Acoust. Soc. Am. 150，4283-4296]的结果，该论文分析了两种流体动力学效应，即压力聚焦和 BM 运动的粘性阻尼，这两种效应都与峰值区域中波数的急剧增加有关，对于二维流体，与标准的一维传输线 WKB 方法相结合进行耳蜗建模。传播方程是从三维流体体积守恒方程中得到的，产生聚焦效应，而粘度的影响表示为对局部一维导纳的修正。具体来说，压力聚焦在不改变峰值导纳的情况下放大 BM 响应，而粘性阻尼通过在速度场中产生急剧梯度来抵消聚焦，从而确定响应峰值的位置。全三维 WKB 形式对于在 BM-流体界面附近表示流体速度场的行为是必要的，这与粘性损耗密切相关。与有限元模型一样，由于粘性，一层薄的流体有效地附着在 BM 上，并且与流体垂直速度的垂直梯度相关联的粘性力通过该层作用在 BM 上。
