人耳耳蜗的双向流固耦合建模分析与主动作用机制研究

发布时间：2018-01-07 18:21

本文关键词：人耳耳蜗的双向流固耦合建模分析与主动作用机制研究　出处：《上海交通大学》2015年博士论文　论文类型：学位论文

【摘要】：经过数千年的进化历程,哺乳动物的听觉系统已经是最复杂的系统之一,人作为高级哺乳动物其听力系统具有十分强大的功能。然而人耳复杂的功能使得人们难以轻易地了解听觉系统的工作机制,尤其是耳蜗作为其中的关键器官,至今人们对它的传声机制还没有完全弄清楚,因此对耳蜗在传声时的力学特性展开研究显得非常必要。本文以提取耳蜗输入阻抗、了解耳蜗的传声机制为目的,通过模型仿真分析与豚鼠耳蜗基底膜振动测试两个方面对耳蜗宏观力学特性和微观力学特性进行了研究,论文主要工作包括以下五个部分。(1)建立了二维的耳蜗流固耦合模型,考虑了耳蜗内流体与基底膜的双向流固耦合作用,分析了基底膜在卵圆窗激励下的响应特性。结果表明:耳蜗基底膜不同位置对不同频率的声音敏感,验证了频率选择特性。利用该模型首次计算了蜗孔大小对耳蜗基底膜响应的影响,并指出:合适的蜗孔大小可以得到合理的基底膜响应,畸形的蜗孔会导致基底膜的振动衰减,从而影响耳蜗的传声特性。分析了圆窗逆向激励耳蜗时基底膜的响应特性,结果表明:逆向激励的耳蜗传声效率略低于正向激励,但基底膜的响应特性基本一致,逆向激励是中耳助听装置驱动耳蜗的一种可能方式。(2)首次使用双向流固耦合方法建立了三维的耳蜗流固耦合模型,分析了耳蜗基底膜、圆窗的位移响应,计算了耳蜗内流体压力的分布情况,提取了耳蜗输入阻抗,并通过耳蜗输入阻抗、基底膜位移响应、耳蜗地图以及耳蜗内流体压力仿真结果与实验值的对比,验证了模型的可靠性。研究结果表明:耳蜗输入阻抗随着频率的变化而变化,在低频区变化平缓,在高频区明显增大;圆窗的振动与卵圆窗输入是反相位的,它起到缓冲耳蜗内流体压力的作用;耳蜗基底膜任一位置只对特定频率的纯音激励最敏感,在该特定频率激励下基底膜该位置的振动最大,且相对于卵圆窗激励的相位滞后明显增加,验证了基底膜的频率选择特性和行波特性;基于双向流固耦合方法的有限元模型不仅可以正确地模拟基底膜的响应,还可以更准确地计算耳蜗内流体压力的分布情况。(3)以局部柯蒂氏器为对象,建立了人耳耳蜗的微观力学模型,给出了系统的运动微分方程,推导了基底膜、盖膜-网织层组合结构以及外毛细胞运动的稳态解。为了与主动耳蜗的实验结果对比,用豚鼠耳蜗的参数代入系统方程中,计算了基底膜在被动耳蜗和主动耳蜗中的响应特性,发现主动耳蜗基底膜的响应具有非线性压缩性和移频特性。首次从理论上分析了主动耳蜗柯蒂氏器各结构运动之间的相位关系,发现外毛细胞的运动超前于组合结构的运动,而组合结构的运动又超前于基底膜的运动,并指出:柯蒂氏器各结构运动之间的相位调制影响着主动耳蜗的放大机制。对比研究了外毛细胞等效非线性阻尼和线性阻尼对主动耳蜗响应的影响,揭示了柯蒂氏器的相位调制的本质原因,并提出:外毛细胞等效非线性阻尼是相位调制的关键因素。(4)由于三维人耳有限元模型中并没有包含主动作用机制,而微观力学模型中考虑了柯蒂氏器的微观机制。故基于微观模型的研究结果,分析微观的被动模型中组合结构对基底膜的作用力关系,同样研究了微观的主动模型中基底膜受力与被动模型中受力的比例关系,将他们应用到三维人耳有限元模型中,分析了组合结构对基底膜响应的影响和含主动力的人耳耳蜗基底膜的传声特性,并指出:组合结构对基底膜的响应特性影响不大;而主动的基底膜响应具有明显的放大效果,且其最大振幅的位置与被动模型相比有所不同。(5)搭建了哺乳动物耳蜗振动测试平台,使用激光多普勒测振仪记录耳蜗基底膜和耳蜗输入处镫骨的振动情况。国内首次测试了镫骨和基底膜在外耳道70、80和90dbspl声激励下的振动响应,结果表明:镫骨的位移幅值在2khz时最大,之后缓慢地降低;基底膜的位移幅值在分析频率范围内有且只有一个峰值,该峰值对应的频率就是基底膜该位置对应的最佳频率;基底膜振动的相位在最佳频率时迅速地降低,与行波特性一致。根据耳蜗响应与耳蜗输入的比值,计算了耳蜗增益,并指出:耳蜗增益与激励强度无关,是耳蜗的固有属性。对比了本文的实验结果与文献报道的实验数据,验证了本文实验的可靠性。通过定性分析,对比了人耳耳蜗有限元模型模拟的基底膜响应与实验测试的豚鼠耳蜗基底膜的响应结果,基底膜的响应特性基本一致,验证了模型的有效性。
[Abstract]:After thousands of years of evolution, the mammalian auditory system is one of the most complicated system, as the hearing system has higher mammals very powerful. However, the human ear complex function makes it difficult to easily understand the working mechanism of the auditory system, especially as the key organs of the cochlea, the transmission mechanism of the people so far it is not fully understood, so the mechanical characteristics of the cochlea in sound when the research is very necessary. This paper to extract the cochlear input impedance, understand the transmission mechanism of cochlear for the purpose, through the analysis and simulation model of guinea pig cochlea basilar membrane vibration test of the two aspects of the Study on the macro mechanical properties and micro mechanical properties of the cochlea and the main work of the thesis includes the following five parts. (1) a two-dimensional cochlear fluid solid coupling model, considering the fluid within the cochlea and Effect of bidirectional flow of basement membrane coupling, analysis of the response characteristics of basement membrane in the oval window under the excitation. The results showed that the basilar membrane at different positions for different sound frequency sensitive, verify the frequency selective characteristics. The influence of pore size on the response, the cochlear basilar membrane were calculated by using the model and point out: worm hole size can get reasonable response of basement membrane, helicotrema deformity will lead to the attenuation of vibration of the basilar membrane, thus affecting the transmission characteristics of the cochlea. Analysis of the response characteristics of the basement membrane of the cochlea round window reverse encouraging results show that the reverse incentive of the cochlea is slightly lower than the sound transmission efficiency of positive incentives, but the response characteristics of the substrate the film is basically the same, the reverse incentive is a possible way to drive the middle ear hearing device cochlea. (2) the two-way flow solid coupling method to establish a three-dimensional cochlear fluid solid coupling model for the first time, analysis of the ear The cochlear basilar membrane displacement response of the round window, the distribution of fluid pressure in the cochlea were calculated from the cochlear input impedance and the input impedance of the cochlear basilar membrane, displacement response, cochlear map and the comparison between the simulation results and the experimental value of fluid pressure in the cochlea, the reliability of the model was verified. The results show that: the cochlear input the impedance changes with the change of frequency in the low-frequency region varies smoothly increases obviously in the high frequency region; the input vibration and the oval window and round window is anti phase, it plays a role in the cochlear fluid pressure buffer; cochlear basal membrane in any position only pure tone excitation of specific frequencies in the most sensitive and specific the frequency of excitation of basement membrane to the location of the maximum vibration, and the phase relative to the oval window incentive lag increased significantly, to verify the characteristics and wave characteristics of basement membrane frequency selection; based on the two-way flow solid coupling method Finite element model can accurately simulate the distribution of basement membrane, but also can accurately calculate the fluid pressure in the cochlea. (3) to the local organ of Corti for micro object, established the mechanical model of human cochlea, the differential equations of motion of the system are given, derived from the basement membrane, steady state cover film - reticular layer composite structure and outer hair cell movement solutions. In order to experimental results and active cochlear contrast with parameters of system equations in guinea pig cochlea in response was calculated in the passive and active cochlear basement membrane in the cochlea, found in response to active cochlear basilar membrane with nonlinear compression and transfer frequency characteristics for the first time. From the theoretical analysis of the phase relationship between the active cochlea Corti structure movement, that movement of outer hair cell movement in advance of the composite structure, the composite structure of movement and leading to the basement membrane The movement, and pointed out that the phase modulation between the organ of Corti the structure movement affects the amplification mechanism of the active cochlea. The response of the outer hair cells of the equivalent nonlinear damping and linear damping on the active cochlea, reveals the essential reason, phase modulation of Corti's organ of outer hair cells and proposed that the equivalent nonlinear damping is a key factor in phase modulation. (4) because of the three-dimensional finite element model of human ear does not contain active mechanism, and the micro mechanical model of senior high school entrance examination considered the microscopic mechanism of Corti's organ. So the research results based on the model of micro structure analysis, combination of the basement membrane in the micro passive force relationship model. Also on the basement membrane active model of micro force and passive model stress ratio, they will be applied to the three-dimensional finite element model of human ear, response of the composite structure of basement membrane The transmission characteristics, influence and active force of human cochlea basement membrane and pointed out that the response characteristic of the composite structure has little effect on basement membrane and the basement membrane; active response has obvious amplification effect, and the position of the maximum amplitude is different compared with the passive model. (5) to build the mammalian cochlea vibration test platform vibration using laser Doppler vibrometer recording and cochlear basilar membrane input. The first test of the domestic stapes stapes and basement membrane in the ear canal and 90dbspl 70,80 vibration response under acoustic excitation, the results show that the displacement amplitude of the stapes in maximum at 2KHz, then slowly decreased; the basilar membrane displacement amplitude analysis of the frequency range has only one peak, the best frequency corresponding to the peak value of frequency is corresponding to the position of the basilar membrane phase; basilar membrane vibration decreased rapidly in the best frequency That is consistent with the characteristics of traveling wave. According to the ratio of the input response of cochlear cochlear, calculate the cochlear gain, and points out that the cochlear gain has nothing to do with the incentive intensity, is the inherent attribute of the cochlea. Compared the experiment results with the experimental data reported in the literature, proves the reliability of this experiment. Through qualitative analysis, comparison base the membrane response and Simulation of the finite element model of human ear cochlea of guinea pig cochlear basilar membrane response, the response characteristics of the basilar membrane is consistent, verify the validity of the model.

【学位授予单位】：上海交通大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：R339.16

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