Distortion product otoacoustic emissions measured as vibration on the eardrum of human subjects
Distortion product otoacoustic emissions measured as vibration on the eardrum of human subjects
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DOI：
10.1073/pnas.0610185103
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发表时间：
2007-01-30
影响因子：
11.1
通讯作者：
Gummer, A. W.
中科院分区：
文献类型：
--
作者：
Dalhoff, E.;Turcanu, D.;Gummer, A. W.
在此之前，在听觉阈区测量人类受试者的耳膜振动是不可能的。建议这样的测量应该提供有关耳蜗中机械放大器状态的信息。正是这个放大器使我们的听觉异常灵敏。在这里，我们介绍了激光多普勒振动计的结果，我们设计了一个无创探测耳蜗力学接近听觉阈值。这个装置可以在体内对人类耳膜进行皮米大小的振动测量。有了这种灵敏度，我们发现鼓膜频率响应线性下降到至少20 db声压级（SPIL）。利用双音调声刺激下耳声发射（dpoae）的三次畸变积来评价非线性耳蜗放大。dpoae源于耳蜗的力学非线性。当刺激频率f(1)和f(2)为f(2)/f(1) = 1.2和f(2) = 4-9.5 kHz，强度L-1和L-2为L-1 = 0.4L(2) + 39 dB和L-2 = 20-65 dB SPIL时，20名受试者的DPOAE位移幅值不超过8 pm，听力损失达16 dB。DPOAE振动与f(2)处的振动呈非线性关系。这种相关性使听阈能够客观、准确地估计出来；阈值估计的标准差仅为8.6 dB SPL。该仪器有望成为区分耳蜗和中耳力学状况的有力工具，具有较高的准确性。
It has previously not been possible to measure eardrum vibration of human subjects in the region of auditory threshold. It is proposed that such measurements should provide information about the status of the mechanical amplifier in the cochlea. It is this amplifier that is responsible for our extraordinary hearing sensitivity. Here, we present results from a laser Doppler vibrometer that we designed to noninvasively probe cochlear mechanics near auditory threshold. This device enables picometer-sized vibration measurements of the human eardrum in vivo. With this sensitivity, we found the eardrum frequency response to be linear down to at least a 20-dB sound pressure level (SPIL). Nonlinear cochlear amplification was evaluated with the cubic distortion product of the otoacoustic emissions (DPOAEs) in response to sound stimulation with two tones. DPOAEs originate from mechanical nonlinearity in the cochlea. For stimulus frequencies, f(1) and f(2), with f(2)/f(1) = 1.2 and f(2) = 4-9.5 kHz, and intensities L-1 and L-2, with L-1 = 0.4L(2) + 39 dB and L-2 = 20-65 dB SPIL, the DPOAE displacement amplitudes were no more than 8 pm across subjects (n = 20), with hearing loss up to 16 dB. DPOAE vibration was nonlinearly dependent on vibration at f(2). The dependence allowed the hearing threshold to be estimated objectively with high accuracy; the standard deviation of the threshold estimate was only 8.6 dB SPL. This device promises to be a powerful tool for differentially characterizing the mechanical condition of the cochlea and middle ear with high accuracy.