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

项目概要/摘要 该项目开发并评估了估计鼓室附近耳道声场的程序 膜（TM）。这些程序的基本框架是将耳道建模为声学模型 波导。通过量化来从声学角度描述耳道横截面积的空间变化 正向和反向声波在插入耳道的探头和靠近耳道的位置之间传播 TM。用声压及其反射和透射来描述 TM 附近的声场 组件可以更准确地量化中耳的声学高频 (HF) 输入。这样一个 描述改进了 TM 附近刺激的 HF 校准，用于耳声学等生理测试 发射和听觉脑干反应，以及高频行为测试，例如扩展听力测定和测试 声音的空间处理。该规范还提高了描述正向和反向的能力 HF 处的耳声发射响应，可非侵入性地编码有关外毛细胞功能的信息 耳蜗内。该项目成果将有利于中耳和耳蜗的声学诊断测试 功能。目标 1 的目标是： (i) 在以下位置实施并评估因果时域测量： 耳朵的声学反射函数 (RF) 的探头尖端，这样反射率就是 RF，(ii) 使用 RF 计算探头尖端和 TM 之间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 3.6 毫米以内）。当前频率- 测量反射率的领域测试并不局限于服从因果关系，这限制了它们的准确性 临床应用，特别是在 8 kHz 以上的频率下。因果关系要求声音不能被反射 在其发生之前。耳朵的射频是后续区域距离计算的关键响应 耳道。 RF 数据将在 Aim 1 实验中在不同面积、耳模的管道系统中采集 耳道和人工耳模拟器（IEC711 耦合器）。目前描述面积距离的方法 耳道函数主要使用韦氏或平面波喇叭方程，其不足 耳道面积变化的准确性。该项目将使用 新颖的球面波喇叭模型，可控制耳道锥度的变化。这些区域距离 算法包括耳道壁损失的新颖时域描述。目标 2 的目标是： (i) 获取听力正常的 5 岁儿童和成人组的 RF 数据，(ii) 计算面积距离 耳道功能，(iii) 使用数字扫描仪测量耳道几何形状，(iv) 比较声学 以及面积-距离函数的扫描测量，(v) 估计声场压力，以及 声音在 TM 附近的传输和反射，以及 (vi) 测试耳道和耳道的成熟差异 儿童中耳功能相对于成人。该方法最大限度地利用了声学数据 通过耳道内的探头测量提供。

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.