Janssen T, Kummer P, Arnold W
Hals-Nasen-Ohren-Klinik, Technische Universitat, München, Germany.
J Acoust Soc Am. 1998 Jun;103(6):3418-30. doi: 10.1121/1.423053.
High-resolution hearing threshold and 2 f1-f2 distortion product otoacoustic emission (DP) were measured with the same in-the-ear sound probe and same calibration at 51 frequencies between 500 and 8000 Hz in 39 sensorineural hearing loss ears associated with tinnitus. Using a primary tone setting L1 = 0.4L2 + 39 that accounts for the nonlinear interaction of the two primary tones at the DP generation site at f2, DPs were elicited in a wide range from L2 = 65 to 20 dB SPL. We failed to find a uniform DP behavior in the 39 tinnitus ears tested. Seventeen of them behaved like impaired ears without tinnitus. In these ears a linearized DP growth was observed where the DP level decreased and the slope of the DP I/O functions steepened with increasing hearing loss and as a result both the DP level and the DP slope strongly correlated with hearing threshold. The other population, 22 tinnitus ears, exhibited a poor or even inverse relationship between DP level and hearing threshold, i.e., displayed an increase of DP level with increasing hearing loss. Despite the severe hearing loss but due to the high level, DPs could be recorded well in the frequency range that corresponded to the appearance of the tinnitus. The DP slope, however, increased with increasing hearing loss and, therefore, did still correlate with hearing threshold revealing pathological alteration. The data suggest that the DP level alone is hardly capable of assessing hearing impairment in tinnitus ears and may even be misleading. Thus just the DP slope seems to be the only reliable indicator of cochlear malfunction around the tinnitus frequency. The observed nonuniform DP behavior suggests different cochlear impairments in tinnitus ears. In those ears where the DP level decreases and the slope of the I/O functions increases with hearing loss, cochlear sensitivity and tuning are supposed to be diminished. In those ears where the DP level increases with increasing hearing loss, a reinforced mechanical distortion is hypothetized to be generated by cochlear hyperactivity that can be the source of both the abnormally high DP level and the tinnitus.
使用同一入耳式探声器并在相同校准条件下，在39例伴有耳鸣的感音神经性听力损失耳中，于500至8000Hz的51个频率处测量了高分辨率听力阈值和2f1 - f2畸变产物耳声发射（DP）。使用主音设置L1 = 0.4L2 + 39，该设置考虑了在f2处DP产生部位两个主音的非线性相互作用，在L2 = 65至20dB SPL的宽范围内引出了DP。在测试的39只耳鸣耳中，我们未能发现一致的DP行为。其中17只耳的表现类似于无耳鸣的听力受损耳。在这些耳中，观察到DP呈线性增长，随着听力损失增加，DP水平下降，DP输入/输出（I/O）函数的斜率变陡，因此DP水平和DP斜率均与听力阈值密切相关。另一组，即22只耳鸣耳，DP水平与听力阈值之间呈现不良甚至相反的关系，即随着听力损失增加，DP水平升高。尽管听力损失严重，但由于DP水平较高，在与耳鸣出现相对应的频率范围内仍能很好地记录到DP。然而，DP斜率随着听力损失增加而增大，因此仍与听力阈值相关，揭示了病理改变。数据表明，仅DP水平很难评估耳鸣耳的听力损伤，甚至可能产生误导。因此，似乎只有DP斜率是耳鸣频率周围耳蜗功能障碍的唯一可靠指标。观察到的DP行为不一致表明耳鸣耳存在不同的耳蜗损伤。在那些随着听力损失DP水平下降且I/O函数斜率增加的耳中，推测耳蜗敏感性和调谐功能降低。在那些随着听力损失增加DP水平升高的耳中，推测耳蜗活动增强会产生增强的机械畸变，这可能是异常高DP水平和耳鸣的来源。
