Exploring otoacoustic emissions with intracochlear pressure measurements

描述(申请人提供)：本申请旨在进一步研究声音能量如何从耳蜗传播出去这一重要问题，并在耳蜗力学和耳声发射之间建立一座桥梁。除了感知声音，耳朵也会发出声音，这是基于细胞的耳蜗线性度的结果。自从1976年这种所谓的“耳声发射”被发现以来，这种能量到底是如何从内耳辐射出来的一直是一个悬而未决的重大问题。这项应用将使用独特而强大的微压传感器来探测耳蜗力学，并使用灵敏的麦克风系统作为接收器来校准声音和测量耳道中的声压。我们将在沙土鼠正常耳中同时直接测量耳腔内压力和耳道压力。耳蜗声失真产物(DPS)是耳道内检测失真产物耳声发射(DPOAEs)的理想声源。耳蜗腔内入路将在耳蜗底转处进行，耳蜗处的机制已在野外和实验室中得到了很好的证实。通过对DPOEs和DPS的直接比较，进一步探讨DPOAEs在反向传播中的作用，包括反向行波和耳蜗液的作用、耳蜗线的非线性以及DPS的“产生器”和“反射器”元件对DPOAEs的贡献。这些测量将极大地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处传播出去的理解。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无法通过其他方式测试听力的患者。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是至关重要的。自从1978年Kemp发现耳声发射(OAEs)以来，内耳究竟如何发出声能一直是一个悬而未决的重大问题。除了感知声音外，由于基于细胞的非线性作用力，耳蜗会产生声音。在耳道中检测到的耳声是一种非侵入性的探头，临床上用于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。最近，在实验室建立了一种同时记录沙土鼠耳内压和电流压的技术，这对了解耳蜗力学有很大的启发作用。这项建议旨在利用耳声发射和耳壳内压的联合研究来探索正常沙土鼠耳蜗体内发射过程的重要方面。该项目的结果将导致对以下具体问题的进一步理解：(1)耳声发射采用的耳内路径；(2)当这些声音从耳蜗外传播时放大的可能性；以及(3)不同耳声发射成分的存在。

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.