HIGH-FREQUENCY DISTORTION PRODUCT OTOACOUSTIC EMISSIONS

失真产物发射，当它是耳朵时， 受到成对音调的刺激，被广泛认为提供了一种有用的 客观测量人类高频听力损失。然而，在这方面， 在这些相同的频率下，通常用于测量辐射的系统 在校准刺激声压时会有很大的误差 程度.这是由于在耳道中存在 声音从鼓膜，导致明显的空间不均匀性， 声音水平。这些错误似乎引入了很大的可变性 在人类受试者群体中采样的排放数据中， 4 kHz以上。此外，这些系统不产生有用的刺激 在人类听觉的最高频率处的强度。 由于高 频率范围对失真具有最大的潜在诊断价值 产品排放，这些问题应尽快解决， 可以为高排放量建立可靠的规范标准， 频率.一个探头管麦克风将直接测量刺激 在耳膜附近。声学和光学方法都将提供 将探头定位在一致位置所需的反馈。这 系统将用于测量听力阈值， 用于测量大样本中畸变产物发射的装置 听力正常的人类实验对象。开发一种高频 声源将首次允许可靠的测量， 在整个听力范围内的失真产物发射。数据 收集的数据应具有足够的可靠性，以批判性地评估 排放测量的潜在诊断效用 频率以及从发射的传输模式 耳蜗到外耳道。这些模型反过来可以用于 预测排放水平之间预期的相关程度， 听力阈值

Distortion product emissions, sounds emitted by the ear when it is stimulated by pairs of tones, are widely thought to offer a useful objective measurement of high-frequency hearing loss in humans. However, at these same frequencies, the systems commonly used to measure emissions are subject to large errors in calibrating the stimulus sound pressure levels. This results from the presence in the ear canal of reflections of sound from the eardrum that lead to pronounced spatial nonuniformities in the sound levels. These errors appear to introduce substantial variability in emission data sampled in populations of human subjects at frequencies above 4 kHz. Furthermore, these systems do not generate usable stimulus intensities at the highest frequencies of human hearing. Since the high frequency range has the greatest potential diagnostic value for distortion product emissions, these problems should be addressed quickly so that reliable normative standards can be established for emissions at high frequencies. A probe tube microphone will directly measure the stimulus level near the eardrum. Both acoustic and optical methods will provide the feedback necessary to position the probe at a consistent location. This System will be used to measure audiometric thresholds with the same apparatus used to measure distortion product emissions in a large sample of human subjects with normal hearing. The development of a high-frequency sound source will allow for the first time reliable measurements of distortion product emissions over the entire hearing range. The data collected should be of sufficiently reliability to evaluate critically the potential diagnostic utility of the emission measurements at high frequencies as well as models of transmission of the emissions from the cochlea to the external ear canal. These models in turn can be used to predict the degree of - correlation expected between emission levels and audiometric thresholds.