Exploring otoacoustic emissions with intracochlear pressure measurements

描述（由申请人提供）：本申请旨在进一步研究声能如何从耳蜗传播的重要问题，并在耳蜗力学和耳声发射之间建立桥梁。除了感知声音，耳朵也发出声音，这是基于细胞的耳蜗非线性的结果。自1976年发现所谓的“耳声发射”以来，这种能量究竟是如何从内耳辐射出来的一直是一个悬而未决的主要问题。该应用将使用独特而强大的微压力传感器探测耳蜗力学，并使用灵敏的麦克风系统作为接收器校准声音并测量耳道内的声压。直接和同时测量声音刺激下沙鼠耳蜗内压力和耳道压力将在沙鼠正常耳中进行。耳蜗畸变产物（DPs）将作为耳道内检测畸变产物耳声发射（dpoae）的理想耳蜗内声源。耳蜗内入路将是耳蜗的基础转路，在这里耳蜗的机制已经在野外和实验室中得到了很好的建立。通过直接比较dpoae和DPs，进一步探讨反向声传播，具体目的是分类反向行波和耳蜗液的作用、耳蜗非线性以及DPs“发生器”和“反射器”分量对dpoae的贡献。这些测量结果将大大提高我们对耳蜗如何被声音激发并产生声音以及声音如何从耳蜗传播出去的理解。这些从耳朵发出的声音在临床上被广泛用于检测和诊断各种形式的听力障碍，特别是在婴儿和其他听力无法通过其他方式检测的患者中。因此，了解它们的产生和传播机制在许多临床和研究应用中至关重要。自1978年Kemp发现耳声发射（oae）以来，声能究竟如何从内耳辐射一直是一个悬而未决的主要问题。除了感知声音，耳蜗也产生声音，作为非线性细胞力的结果。这些“耳蜗产生的”声音，即在耳道中检测到的oae，是一种非侵入性探头，用于临床检测和诊断听力障碍。因此，了解它们的产生和传播机制对许多临床和研究应用至关重要。近年来，在实验室中建立了沙鼠耳蜗内压力和耳蜗内压力的同时记录技术，这对理解耳蜗力学具有重要的启示意义。本研究旨在通过对耳蜗内压力和耳蜗内发射过程的联合研究，探索正常沙鼠耳蜗内发射过程的重要方面。该项目的结果将有助于进一步理解以下具体问题：(1)耳蜗内声发射的路径；(2)这些声音在耳蜗外传播时被放大的可能性；(3)不同耳蜗声发射成分的存在。

DESCRIPTION (provided by applicant): This application aims to further investigate the important issue of how sound energy travels out of the cochlea and to provide a bridge between cochlear mechanics and otoacoustic emissions. In addition to perceiving sound, the ear also makes sound, as a result of the cell-based cochlear nonlinearity. Exactly how this energy radiates from the inner ear has been a major unresolved question since the discovery of these so-called "otoacoustic emissions" in 1976. This application will use the unique and powerful micro-pressure-sensor to probe the cochlear mechanics and a sensitive microphone system as the receiver to calibrate sound and measure the sound pressure in the ear canal. Direct and simultaneous measurements of the intracochlear pressure and ear canal pressures to sound stimuli will be performed in gerbil normal ears in vivo. Cochlear distortion products (DPs) will be used as the ideal intracochlear sound sources of the distortion product otoacoustic emissions (DPOAEs) being detected in the ear canal. The intracochlear approach will be at the basal turn of cochlea, where the cochlear mechanism has been well established in the field and also in the lab. By directly comparing the DPOAEs and DPs, the sound transmission in reverse direction will be further explored with the specific aims to category the role of the reverse traveling wave and the cochlear fluid, the cochlear nonlinearity and the contributions of DPs 'generator' & 'reflector' components to DPOAEs. The measurements will significantly improve our understanding of how the cochlea is excited by and produces sound and how the sound travels out of the cochlea. These sound emissions from the ear are widely used in clinic to detect and diagnose forms of hearing impairment, especially in infants and other patients whose hearing cannot be tested in other ways. Understanding the mechanisms of their generation and transmission is therefore crucial in many clinical and research applications. How exactly sound energy radiates from the inner ear has been a major unresolved question since the discovery of otoacoustic emissions (OAEs) in 1978 by Kemp. In addition to perceiving sound, the cochlea also generates sound, as a result of nonlinear cell-based forces. These 'cochlea-generated' sounds, known as OAEs being detected in the ear canal, are a noninvasive probe used in the clinic to detect and diagnose hearing impairment. Understanding the mechanisms of their generation and transmission is therefore crucial to many clinical and research applications. Recently a simultaneous recording technique of intracochlear pressure and EC pressure in gerbils has been well established in the lab, which has proven to be very illuminating for understanding cochlear mechanics. This proposal aims to use this combined studies of OAEs and intracochlear pressure to probe important aspects of the emission process in normal gerbil cochlea in vivo. The results of this project will lead to further understanding on the specific questions of (1) the intracochlear path OAEs take and (2) the possibility for amplification as these sounds travel out of the cochlea, and (3) the presence of different OAE components.