MEASUREMENT OF ACOUSTIC-IMPEDANCE AND REFLECTANCE IN THE HUMAN EAR CANAL
MEASUREMENT OF ACOUSTIC-IMPEDANCE AND REFLECTANCE IN THE HUMAN EAR CANAL
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DOI：
10.1121/1.408329
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发表时间：
1994-01-01
影响因子：
2.4
通讯作者：
ALLEN, JB
中科院分区：
文献类型：
--
作者：
VOSS, SE;ALLEN, JB
压力反射率R（ω）是传递函数，其可以通过反射复数压力除以入射复数压力的比率来针对线性单端口网络定义。反射率是与1端口的阻抗密切相关的函数。能量反射率R（Ω）被定义为\R\2。它表示反射能量与入射能量的比率。在人耳道中，能量反射率是重要的，因为它是中耳和耳蜗的无效性的量度，并且因为其简单的频域解释所提供的洞察力。人们可以通过使用压力反射率及其大小来表征耳道阻抗，从而避开了以下困难问题：（a）从测量点到鼓膜的未知耳道长度，（B）鼓膜的复杂几何形状，以及（c）耳道中的横截面积作为距离的函数而变化。这里报告的是声阻抗测量，观察耳道，对10名听力正常的年轻人（18-24岁）进行测量。椎管内的测量点距离椎管入口约0.85 cm。从这些测量，在运河中的压力反射率计算和阻抗和反射率测量从0.1到15.0 kHz之间的耳朵进行比较。测定了十个受试者的平均反射率和反射率的标准差。两个常见的耳模拟器，Bruel & Kjaer 4157和工业研究产品DB-100（Zwislocki）耦合器的阻抗和反射率也进行了测量，并与人类的平均测量值进行比较。所有测量都是使用控件进行的，这些控件确保了受试者之间声学校准的一致精度。这是通过使用两个阻抗已知的标准声电阻器来实现的。从实验结果，它的结论是，有显着的主题的变化幅度的反射率为10耳道。这种可变性被认为是由于耳蜗和中耳阻抗差异。试图在建模的反射率，但如本文所讨论的，目前有几个问题站在这些模型的方式。这种模型对于声学虚拟现实系统和有源噪声控制耳机将是有用的。
The pressure reflectance R (omega) is the transfer function which may be defined for a linear one-port network by the ratio of the reflected complex pressure divided by the incident complex pressure. The reflectance is a function that is closely related to the impedance of the 1-port. The energy reflectance R(omega) is defined as \R\2. It represents the ratio of reflected to incident energy. In the human ear canal the energy reflectance is important because it is a measure of the inefficiency of the middle ear and cochlea, and because of the insight provided by its simple frequency domain interpretation. One may characterize the ear canal impedance by use of the pressure reflectance and its magnitude, sidestepping the difficult problems of (a) the unknown canal length from the measurement point to the eardrum, (b) the complicated geometry of the drum, and (c) the cross-sectional area changes in the canal as a function of distance. Reported here are acoustic impedance measurements, looking into the ear canal, measured on ten young adults with normal hearing (ages 18-24). The measurement point in the canal was approximately 0.85 cm from the entrance of the canal. From these measurements, the pressure reflectance in the canal is computed and impedance and reflectance measurements from 0.1 to 15.0 kHz are compared among ears. The average reflectance and the standard deviation of the reflectance for the ten subjects have been determined. The impedance and reflectance of two common ear simulators, the Bruel & Kjaer 4157 and the Industrial Research Products DB-100 (Zwislocki) coupler are also measured and compared to the average human measurements. All measurements are made using controls that assure a uniform accuracy in the acoustic calibration across subjects. This is done by the use of two standard acoustic resistors whose impedances are known. From the experimental results, it is concluded that there is significant subject variability in the magnitude of the reflectance for the ten ear canals. This variability is believed to be due to cochlear and middle ear impedance differences. An attempt was made at modeling the reflectance but, as discussed in the paper, several problems presently stand in the way of these models. Such models would be useful for acoustic virtual-reality systems and for active noise control earphones.