Moulin A, Bera J C, Collet L
Physiologie Sensorielle Audition et Voix, Unité associée au CNRS 1447, Hôpital Edouard-Herriot, Lyon, France.
Audiology. 1994 Nov-Dec;33(6):305-26. doi: 10.3109/00206099409071890.
As other types of otoacoustic emissions, distortion product otoacoustic emissions (DPOAEs) allow the exploration of the active cochlear mechanisms known to take place in the outer hair cell system. Most authors consider that 2f1-f2 DPOAEs are generated in a cochlear region corresponding to the geometric mean (GM) of the primary frequencies. To verify the relevance of this hypothesis in clinical practice, DPOAEs were recorded at seven different frequencies, ranging from 0.5 to 4 kHz, in 81 hearing-impaired patients and in 24 normally hearing subjects. To test the hypothesis that DPOAEs reflect the hearing threshold at the frequency of the GM rather than at the 2f1-f2 frequency, this study compares the 2f1-f2 frequency and the GM of the primaries to the frequency of hearing loss. DPOAEs can be used to explore a large range of frequencies, especially at high frequencies, but responses at low frequencies are less reliable due to noise contamination. Secondly, DPOAEs can be recorded in ears that have a hearing threshold as high as 65 dB HL at the frequency corresponding to the GM of the primaries. Finally, DPOAE recordings show frequency specificity: i.e., hearing loss at a specific frequency correlates best with DPOAEs whose GM of primary frequencies corresponds to the frequency of the hearing loss. However, this frequency specificity is still unsatisfactory and decreases as the levels of primaries increase above 60 dB SPL. Moreover, DPOAE amplitude is too variable to predict hearing loss at a particular frequency, whereas DPOAE threshold allows a correct prediction of abnormal auditory threshold in more than 80% of the cases at frequencies above 1 kHz.
与其他类型的耳声发射一样，畸变产物耳声发射（DPOAE）有助于探究已知在外毛细胞系统中发生的主动耳蜗机制。大多数作者认为，2f1-f2 DPOAE是在与初级频率的几何平均数（GM）相对应的耳蜗区域产生的。为了验证这一假设在临床实践中的相关性，在81名听力受损患者和24名听力正常的受试者中，于0.5至4kHz的七个不同频率记录了DPOAE。为了检验DPOAE反映的是GM频率而非2f1-f2频率处的听力阈值这一假设，本研究将2f1-f2频率和初级频率的GM与听力损失频率进行了比较。DPOAE可用于探究大范围的频率，尤其是高频，但由于噪声干扰，低频处的反应不太可靠。其次，在初级频率GM对应的频率处听力阈值高达65dB HL的耳朵中也可记录到DPOAE。最后，DPOAE记录显示出频率特异性：即特定频率的听力损失与初级频率GM对应于听力损失频率的DPOAE相关性最佳。然而，这种频率特异性仍然不尽人意，并且随着初级频率水平高于60dB SPL而降低。此外，DPOAE幅度变化太大，无法预测特定频率的听力损失，而DPOAE阈值在1kHz以上频率的80%以上病例中能够正确预测异常听觉阈值。
