Boys Town National Research Hospital, 555 North 30th Street, Omaha, NE 68131, USA.
J Assoc Res Otolaryngol. 2012 Oct;13(5):591-607. doi: 10.1007/s10162-012-0336-1. Epub 2012 Jun 12.
The total sound pressure measured in the ear canal may be decomposed into a forward- and a reverse-propagating component. Most of the reverse-propagating component is due to reflection at the eardrum. However, a measurable contribution to the reverse-propagating component comes from the cochlea. Otoacoustic emissions (OAEs) are associated with this component and have been shown to be important noninvasive probes of cochlear function. Total ear-canal reflectance (ECR) is the transfer function between forward and reverse propagating components measured in the ear canal. Cochlear reflectance (CR) is the inner-ear contribution to the total ECR, which is the measured OAE normalized by the stimulus. Methods are described for measuring CR with a wide-band noise stimulus. These measurements offer wider bandwidth and minimize the influence of the measurement system while still maintaining features of other OAEs (i.e., frequency- and level-dependent latency). CR magnitude decreases as stimulus level increases. Envelopes of individual band-limited components of the time-domain CR have multiple peaks with latencies that persist across stimulus level, despite a shift in group delay. CR has the potential to infer cochlear function and status, similar to other OAE measurements.
在耳道中测量到的总声压可分解为正向和反向传播分量。反向传播分量的大部分是由于鼓膜的反射引起的。然而，来自耳蜗的反射也会对反向传播分量产生可测量的贡献。耳声发射（OAE）与该分量相关联，并且已被证明是耳蜗功能的重要非侵入性探针。总耳道反射率（ECR）是在耳道中测量的正向和反向传播分量之间的传递函数。耳蜗反射率（CR）是总 ECR 中的内耳贡献，它是通过刺激归一化的测量 OAE。本文描述了使用宽带噪声刺激测量 CR 的方法。这些测量方法提供了更宽的带宽，并最大限度地减少了测量系统的影响，同时仍然保持了其他 OAE 的特征（即频率和水平相关的潜伏期）。随着刺激水平的增加，CR 幅度减小。时域 CR 的各个带限分量的包络具有多个峰值，其潜伏期在整个刺激水平上保持不变，尽管群延迟发生了变化。CR 有可能像其他 OAE 测量一样推断耳蜗功能和状态。
