Otoacoustic Emission Cochleography

描述（由申请人提供）：计划中的研究旨在更好地理解dpoae产生的机制，以及这种发射的大而复杂的响应空间的关键特征。这一总体目标是通过使用DPOAE电平/相位（L/P）图来实现的，该图将DPOAE的幅度和相位视为f2/f1比和DPOAE频率的函数。根据普遍接受的DPOAE产生的2源模型，在这些图中，水平相位带（浅相位斜率vs. fdp）表示来自f2位置的失真源发射，而垂直相位带（陡相位斜率vs. fdp）表示来自DPOAE频率位置（fdp）的反射发射。最近，我们发现，在这些图中，位于fdp附近的干扰音（ITs）无法去除人类在较高原音水平下的所有垂直相位带，也无法提取兔在存在垂直相位带时的任何dpoae反射成分。目的1研究了一种假设，即在fdp附近不受ITs影响的垂直相位带取决于原音水平、种类和sfoae。因此，我们将比较兔、龙猫和人类在fdp附近不同f1和f2水平下的DPOAE L/P图，并将其与sfoae的存在联系起来，这是反射机制的一个标志。假设在fdp附近对ITs难降解的oae是由分布的dpoae基础源产生的，因此这些发射的开始潜伏期应该比相同f2下获得的畸变发射短。目标#2关注的假设是，根据原音水平和物种，用IFFT方法提取的DPOAE成分可能与IT技术揭示的DPOAE成分不匹配，因为尽管人类和兔子都表现出浅和陡的相位梯度DPOAE成分，但他们对ITs近fdp的响应不同。目标#3调查了DPOAE的基本来源在DPOAE残差中起重要作用的概念，这些残差由高于f2的音调或噪声带显示。这种来源也起到“填补”传统dp图显示的功能障碍区域的作用。这个基础来源的可能性将通过确定不同的音调（f2-f1）可以产生不同水平的f1和f2的八度范围来研究。相对于f2的低频截止值越来越高的噪声带和位于f2以上连续0.33倍频增量的ITs，将用于揭示噪声破坏后DPOAE L/P图中的异常残差，并有助于确定DPOAE基本源的存在和性质。最后，在有4 khz噪声引起的凹痕的人的听音图中，将在有或没有IT高于2 0.33八度的情况下收集DP-gram，以确定是否像在兔子中一样，相应的DP-gram凹痕的真实范围部分被基础DPOAE源掩盖。计划中的研究有望改变关于DPOAE产生机制的公认智慧，并可能导致DPOAE测试的发展，该测试通过允许在更高的原音水平下揭示准确的耳蜗损伤模式而更有用，其中信噪比显着提高。我们对失真产品耳声发射的大部分理论理解是基于低水平的声刺激。拟议的研究将这些努力扩展到更临床相关的水平，其中基础生成器似乎模糊了细胞损伤模式。了解这些机制可能最终允许更准确地描述耳蜗功能障碍的模式，并改善临床上表现出特殊听力障碍的患者的信噪比。

DESCRIPTION (provided by applicant): The planned research is designed to provide an improved understanding of the mechanisms underlying both the generation of DPOAEs as well as the key features of this emission's large, complex response space. This general aim is being accomplished by using DPOAE level/phase (L/P) maps that consider both DPOAE magnitude and phase as a function of f2/f1 ratio and DPOAE frequency. According to the commonly accepted 2-source model of DPOAE generation, in these maps, horizontal-phase banding (shallow phase slope vs. fdp) is indicative of distortion-source emissions from the f2 place, while vertical-phase banding (steep phase slope vs. fdp) signifies reflection emissions from the DPOAE-frequency place (fdp). Recently, we discovered that interference tones (ITs) placed near fdp in these maps were unable to remove all vertical-phase banding at higher primary-tone levels in humans, or to extract any DPOAE-reflection components in the presence of vertical-phase banding in rabbits. Aim #1 investigates the hypothesis that vertical-phase banding refractory to ITs near fdp depends on primary-tone level, species, and SFOAEs. Thus, DPOAE L/P maps from rabbits, chinchillas, and humans collected with and without an IT near fdp at various f1 and f2 levels will be compared, and related to the presence of SFOAEs, a signature of the reflection mechanism. It is postulated that OAEs refractory to ITs near fdp arise from a distributed basal source of DPOAEs and therefore onset latencies of these emissions should be shorter than distortion emissions obtained for the same f2. Aim #2 focuses on the hypothesis that depending upon primary-tone levels and species, DPOAE components extracted with IFFT methods may not match those revealed by IT techniques because, while both humans and rabbits exhibit shallow and steep phase-gradient DPOAE components, they differ in their response to ITs near fdp. Aim #3 investigates the notion that a basal source of DPOAEs plays a substantial role in DPOAE residuals revealed by tones or bands of noise above f2. This source also acts to `fill in' regions of dysfunction as revealed by traditional DP-grams. The likelihood of this basal source will be investigated by determining the octave extent over which difference tones (f2-f1) can be produced for various levels of f1 and f2. Noisebands with increasingly higher low-frequency cutoffs with respect to f2 and ITs placed at successive 0.33-octave increments above f2 will be used to reveal abnormal residuals in DPOAE L/P maps following noise damage and help establish the presence and properties of a basal source of DPOAEs. Finally, DP-grams will be collected with and without an IT 0.33 octaves abovef2 in humans with 4-kHz noise-induced notches in their audiograms to determine if, as in rabbits, the true extent of the corresponding DP-gram notch is partially obscured by a basal DPOAE source. The planned studies promise to modify accepted wisdom regarding mechanisms of DPOAE generation, and may also lead to the development of DPOAE tests that are more useful by allowing accurate cochlear-damage patterns to be revealed at higher primary-tone levels where signal-to-noise ratios are notably improved. The majority of our theoretical understanding of distortion product otoacoustic emissions is based on low-level acoustic stimulation. The proposed studies extend these efforts to more clinically relevant levels where basal generators appear to obscure cellular damage patterns. Understanding these mechanisms may eventually permit a more accurate depiction of the pattern of cochlear dysfunction with improved signal-to-noise ratios for clinic patients exhibiting particular hearing impairments.