Kowalska S, Sułkowski W
ENT and Audiology Division, Nofer Institute of Occupational Medicine, Lódź, Poland.
Int J Occup Med Environ Health. 1997;10(4):441-59.
Click-evoked otoacoustic emission (c-EOAE) was analysed in a group of 122 males (= 244 ears) occupationally exposed to industrial noise levels of 89-94 dB (A). The highest intensity of cochlear responses was observed at 1 and 2 kHz, while at the higher frequencies (3-4 kHz), c-EOAE spectrum was contracted proportionally to the level of the hearing loss and duration of occupational exposure to noise. If hearing loss in pure-tone audiometry exceeded 30 dB HL at 1 kHz and 40 dB at 2 and 4 kHz, c-EOAE was absent. The analysis of the relationship between c-EOAE spectrum and hearing threshold in pure-tone audiogram showed correlation (R = 0.43 to 0.48, at p < 0.01) between distribution of emission energy and hearing threshold at the same range of frequencies. It was found that the c-EOAE amplitudes as well as the values of c-EOAE energy in the noise-exposed people were lower by about 3 dB SPL than in the controls, especially at 4 kHz even in cases of pure-tone hearing thresholds < or = 20 dB HL. This study indicates that, owing to c-EOAE, it is possible to detect a slight noise-induced cochlear lesion which may be overlooked in pure-tone audiometry.
对一组122名职业暴露于89 - 94 dB(A)工业噪声水平的男性（共244耳）进行了瞬态诱发耳声发射（c - EOAE）分析。在1 kHz和2 kHz处观察到耳蜗反应的最高强度，而在较高频率（3 - 4 kHz），c - EOAE频谱与听力损失程度和职业噪声暴露持续时间成比例收缩。如果纯音听力计测试中1 kHz处听力损失超过30 dB HL，2 kHz和4 kHz处超过40 dB HL，则不存在c - EOAE。对c - EOAE频谱与纯音听力图中听力阈值之间关系的分析表明，在相同频率范围内，发射能量分布与听力阈值之间存在相关性（R = 0.43至0.48，p < 0.01）。研究发现，噪声暴露人群的c - EOAE幅度以及c - EOAE能量值比对照组低约3 dB SPL，尤其是在4 kHz处，即使在纯音听力阈值≤20 dB HL的情况下也是如此。这项研究表明，借助c - EOAE，可以检测到轻微的噪声性耳蜗病变，而这种病变在纯音听力测试中可能会被忽视。
