CAUSALITY CONSTRAINTS ON EAR-CANAL TESTS OF ACOUSTIC REFLECTION FUNCTION AND REFLECTANCE

项目概要/摘要 这个项目开发和评估程序，以估计耳道声场附近的鼓膜 膜（TM）。这些程序的基本框架是将耳道建模为声学模型。 波导管耳道的横截面积的空间变化通过量化 在插入耳道的探头和耳道附近的位置之间行进的正向和反向声波 TM.用声压及其反射和透射描述TM附近的声场 该组件可以更准确地量化输入到中耳的声学高频（HF）。这样的 本说明书改进了用于生理测试的TM附近的刺激的HF校准， 发射和听觉脑干反应，以及HF行为测试，如扩展测听和测试 声音的空间处理。该规范还提高了正向和反向描述的能力 高频处的耳声发射响应，其非侵入性地编码关于外毛细胞功能的信息 在耳蜗内。该项目的成果将有益于中耳和耳蜗的声学诊断测试 功能目标1的目标是：（i）在目标1处实施和评估因果时域测量， 探头尖端的耳声反射函数（RF），使得反射率是耳声反射函数（RF）的傅里叶变换。 （ii）使用RF来计算探针尖端和TM之间的耳道的面积-距离函数，以及 (iii)使用RF和区域数据来估计TM附近的声场（即，在3.6毫米以内）。当前频率- 测量反射率的域测试不受因果关系的约束，这限制了它们的准确性， 临床应用，特别是在8 kHz以上的频率。因果关系要求声音不能被反射 在其发生之前。耳朵的RF是用于随后的区域距离计算的关键响应。 耳道在Aim 1实验中，将在具有不同面积、耳模的管道系统中采集RF数据 耳道和人工耳模拟器（IEC 711耦合器）。目前的方法来描述面积距离 耳道中的功能主要使用韦伯斯特或平面波喇叭方程，这是不充分的 耳道面积变化的准确性。本项目将使用 新型球面波喇叭模型，控制耳道锥度的变化。这些区域距离 算法包括对耳道壁处的损耗的新颖时域描述。目标2的目标是： (i)在5岁儿童和听力正常的成年人中采集RF数据，（ii）计算面积距离 （iii）使用数字扫描仪测量耳道几何形状，（iv）比较声学 以及所述面积-距离函数的扫描测量，（v）估计所述声场压力，以及 传输和反射的声音，TM附近，和（六）测试耳道和 儿童中耳功能相对于成人。该方法最大限度地利用了声波数据 提供在耳道内的探针测量中。

PROJECT SUMMARY/ABSTRACT This project develops and evaluates procedures to estimate the ear-canal sound field near the tympanic membrane (TM). The underlying framework of these procedures is to model the ear canal as an acoustic waveguide. Spatial variation in the cross-sectional area of the ear canal is described acoustically by quantifying forward and reverse sound waves traveling between a probe inserted into the ear canal and a location near the TM. Describing the sound field near the TM in terms of sound pressure and its reflected and transmitted components more accurately quantifies the acoustical high frequency (HF) input to the middle ear. Such a description improves HF calibration of the stimulus near the TM for physiological tests such as otoacoustic emission and auditory brainstem responses, and HF behavioral tests such as extended audiometry and tests of spatial processing of sound. The specification also improves the ability to describe forward and reverse otoacoustic emission responses at HFs, which non-invasively encode information on outer-hair cell function within the cochlea. The project outcomes will benefit acoustic diagnostic tests of middle-ear and cochlear function. The goals of Aim 1 are to: (i) implement and evaluate a causal, time-domain measurement at the probe tip of the acoustic reflection function (RF) of the ear, such that reflectance is the Fourier transform of the RF, (ii) use the RF to calculate area-distance functions of the ear canal between the probe tip and TM, and (iii) use RF and area data to estimate the sound field near the TM (i.e., to within 3.6 mm). Current frequency- domain tests to measure reflectance are not constrained to obey causality, which limits their accuracy in clinical applications, especially at frequencies above 8 kHz. Causality requires that sound cannot be reflected prior to its incidence. The RF of the ear is a key response for subsequent area-distance calculations within the ear canal. RF data will be acquired in Aim 1 experiments in tubing systems with varying areas, molds of ear canals and an artificial ear simulator (IEC711 coupler). Present approaches to describe the area-distance function in the ear canal largely use the Webster, or plane-wave, horn equation, which is of insufficient accuracy for the area variations in the ear canal. This project will measure area-distance functions using a novel spherical-wave horn model that controls for changes in the taper of the ear canal. These area-distance algorithms include a novel time-domain description of losses at the ear-canal walls. The goals of Aim 2 are to: (i) acquire RF data in groups of 5-year-old children and adults with normal hearing, (ii) calculate area-distance functions in their canal, (iii) use a digital scanner to measure the ear-canal geometry, (iv) compare acoustic and scanned measurements of the area-distance function, (v) estimate the sound field pressure, and transmission and reflection of sound, near the TM, and (vi) test for maturational differences in ear-canal and middle-ear function in children relative to adults. The approach makes maximal use of the acoustic data provided in a probe measurement within the ear canal.