Christensen Anders T, Abdala Carolina, Shera Christopher A
Auditory Research Center, Caruso Department of Otolaryngology, Keck School of Medicine, University of Southern California, 1640 Marengo St, Los Angeles, CA 90033, USA.
AIP Conf Proc. 2018 May 31;1965(1). doi: 10.1063/1.5038495.
Distortion-product otoacoustic emission (DPOAE) phase is shaped by interaction between the evoking stimulus waves. Near-invariant at high frequencies, DPOAE phase-vs-frequency functions measured at fixed ratios bend into sloping functions at low frequencies. The different phase behaviors observed suggest that the mechanics underlying the generation of OAEs differ in the halves of the cochlea. To map out the phenomenological extent of low-to-mid frequency phase bends, this study recorded DPOAE responses from 20 normal-hearing human adult ears for a wide range of stimulus frequencies, and , where frequency sweeps from 0.25 to 8 kHz, and the / ratio varies from 1.05 to 1.49. Our preliminary results show two transitions in the phase slopes. One near 2.6 kHz in agreement with the literature, and another of opposite polarity near 0.75 kHz which has not been reported before. We find that the frequencies marking these defining phase features are invariant with stimulus ratio. Even as the underlying mechanics remain unknown, the invariance opens the door for DPOAE phase to reliably characterize apical-basal differences across age groups and species.
畸变产物耳声发射（DPOAE）相位由诱发刺激波之间的相互作用形成。在高频时近乎不变，在固定比例下测量的DPOAE相位与频率函数在低频时会弯曲成倾斜函数。观察到的不同相位行为表明，耳声发射产生的机制在耳蜗的两半部分有所不同。为了描绘低频到中频相位弯曲的现象学范围，本研究记录了20名听力正常的成年人类耳朵在广泛刺激频率下的DPOAE反应，其中频率从0.25 kHz扫至8 kHz，且f2/f1比例从1.05变化到1.49。我们的初步结果显示相位斜率有两个转变。一个在2.6 kHz附近，与文献一致，另一个在0.75 kHz附近，极性相反，此前尚未见报道。我们发现标记这些决定性相位特征的频率与刺激比例无关。即使潜在机制仍然未知，但这种不变性为DPOAE相位可靠地表征不同年龄组和物种的顶底差异打开了大门。
