REVERSE MIDDLE EAR SOUND TRANSMISSION

在过去的15年里，越来越多的证据表明， 健康的耳朵不仅能感知声音，还能发出声音。这 “反向能量流”可以通过一个音调，多个音调，或 次点击此外，许多耳朵也产生声音，在没有任何 故意刺激;即声音是自发产生的。在所有 例反向能量流起源于耳蜗，穿过耳蜗， 中耳，并且可以测量为耳道中的耳声发射。 耳声发射测量的可及性使他们 客观评价耳蜗功能的有用工具。然而，在这方面， 关于中耳对耳声的影响知之甚少 例如，这些排放如何受到中耳炎的影响， 病理该项目旨在调查中耳的影响， 通过正常和病理中耳反向传播。 将使用人颞骨标本直接测量反向 传输声音将在内耳中产生， 在前庭安装了一个定制的微型液压声源。的 由此产生的内耳声压将用微型 水听器与灵敏探管法测量耳道压力 麦克风。两个压力之比为反向压力 传递函数这将是第一次测量落后 在人耳中传播。中耳输入阻抗和前向 压力传递函数也将在相同的制备中测量。 前后进行的前向和反向传输测量 中耳的特殊手术修改-例如穿刺 的鼓膜，中断的听小骨，并固定 听小骨-将（1）经验性地描述某些 中耳病变和（2）使精确的数学模型 描述中耳的功能。模型和测量 将用于预测中耳病变对耳道的影响 耳声发射测量。

In the past fifteen years there has been more and more evidence that a healthy ear not only detects sound but also generates sounds. This "reverse energy flow" can be evoked by either a tone, multiple tones, or clicks. In addition, many ears also generate sounds in the absence of any deliberate stimulation; that is sound is generated spontaneously. In all cases reverse-energy-flow originates in the cochlea, travels through the middle-ear and can be measured as otoacoustic emissions in the ear canal. The accessibility of otoacoustic emissions to measurements has made them a useful tool for objective evaluation of cochlear function. However, little is known about the effect of the middle-ear on otoacoustic emissions; for instance how are these emissions affected by middle-ear pathology. This project seeks to investigate the effect of the middle ear in reverse transmission through normal and pathological middle ears. A human temporal bone preparation will be used to directly measure reverse transmission. Sound will be generated in the inner-ear by coupling a custom built miniature hydro sound source into the vestibule. The resulting inner-ear sound pressure will be measured with a miniature hydrophone and the ear canal pressure measured with a sensitive probe-tube microphone. The ratio of the two pressures is the reverse pressure transfer function. These will be the first measurements of backward transmission in a human ear. The middle-ear input impedance and forward pressure transfer function will also be measured in the same preparations. The forward and reverse transmission measurements made before and after specific surgical modifications of the middle-ear - for example puncture of the tympanic membrane, interruption of the ossicles, and fixation of the ossicles - will both (1) empirically describe the effect of certain middle-ear pathologies and (2) enable a precise mathematical model description of the function of the middle ear. The model and measurements will be used to predict the effect of middle-ear pathology on ear canal otoacoustic emission measurements.