Tanaka Y
Department of Otolaryngology, Tokyo Medical College.
Nihon Jibiinkoka Gakkai Kaiho. 1996 Jan;99(1):65-78. doi: 10.3950/jibiinkoka.99.65.
Distortion product otoacoustic emissions (DPOAEs) and frequency difference limens (FDLs) were recorded in each of 10 ears with a sensorineural hearing loss of the dip-type and with sharp-cut high frequency hearing loss. DPOAEs were recorded with an Otodynamic Analyser ILO92 (ver. 1.35) at a f2/f1 frequency ratio 1.2. The distortion-product level (DP level) at 2f1-f2 was measured at 11 points at f2 frequencies between 696 Hz and 6348 Hz and at 26 points at f2 frequencies between 708 Hz and 6165 Hz in the dip-typed and the sharp-cut high frequency hearing loss patients, respectively. The stimulus intensity of primaries was fixed at 70 dBSPL at L and 60 dBSPL at L2. Graphs of DP levels versus f2 frequency (DP-gram) were plotted. FDLs were measured to use "same" or "different" method. Estimates of FDL were obtained at the same frequencies at 11 points from 696 Hz to 6348 Hz as f2 of DPOAE and at sensation levels from 25 dB to 35 dB. As a control, DPOAEs and FDLs were measured in 30 and 50 normal young adults, respectively. The following results ane conclusions were obtained: 1. The DP-gram obtained from 30 normal-hearing ears showed two peaks, at around 1.5 kHz and 5 kHz. 2. DP-grams were similar to Békésy audiograms in frequency specificity in 20 hearing-impaired ears. 3. DP-grams with a f2 abscissa were more similar in shape to Békésy audiograms than DP-grams with a (f1 x f2)1/2 abscissa. 4. The FDLs obtained in 50 normal-hearing ears showed an approximately linear increase in log delta F versus logarithmic frequency of stimuli up to 5 kHz. 5. FDLs at the DPOAE frequencies below the noise level in 20 hearing-impaired ears were greater than two standard deviations from the value for normal-hearing ears. 6. A significant correlation between DPOAEs and hearing threshold levels (HTLs) was found in the 20 ears of the hearing impaired. 7. Significant correlations between DPOAEs and FDL ratios (FDLs in hearing-impaired ears divided by FDLs in normal-hearing ears) were found in these 20 ears, although the correlation coefficient was not as high in the 10 ears with a sharp-cut high frequency hearing loss as in the 10 ears with the dip-typed hearing loss. These results suggested that DPOAEs might serve as an objective indicator of frequency discrimination. Care should be taken, however not to generalize this suggestion to all kinds of hearing loss patients.
对10例呈陡降型感音神经性听力损失和高频陡降型听力损失的患者的每只耳朵记录畸变产物耳声发射（DPOAE）和频率差阈（FDL）。使用Otodynamic Analyser ILO92（版本1.35）在f2/f1频率比为1.2时记录DPOAE。在2f1 - f2处的畸变产物水平（DP水平）在陡降型和高频陡降型听力损失患者中，分别在f2频率为696 Hz至6348 Hz的11个点以及f2频率为708 Hz至6165 Hz的26个点进行测量。初级刺激强度在L1处固定为70 dB SPL，在L2处固定为60 dB SPL。绘制DP水平与f2频率的关系图（DP图）。使用“相同”或“不同”方法测量FDL。在与DPOAE的f2相同的频率，即从696 Hz至6348 Hz的11个点以及感觉水平为25 dB至35 dB时获得FDL估计值。作为对照，分别在30名正常年轻成年人和50名正常年轻成年人中测量DPOAE和FDL。得到了以下结果和结论：1. 从30只正常听力耳朵获得的DP图显示在约1.5 kHz和5 kHz处有两个峰值。2. 在20只听力受损耳朵中，DP图在频率特异性方面与Békésy听力图相似。3. 以f2为横坐标的DP图在形状上比以（f1×f2）1/2为横坐标的DP图更类似于Békésy听力图。4. 在50只正常听力耳朵中获得的FDL显示，在刺激频率的对数达5 kHz之前，log ΔF与刺激频率的对数大致呈线性增加。5. 在20只听力受损耳朵中，低于噪声水平的DPOAE频率处的FDL比正常听力耳朵的值大两个标准差以上。6. 在20只听力受损耳朵中发现DPOAE与听力阈值水平（HTL）之间存在显著相关性。7. 在这20只耳朵中发现DPOAE与FDL比率（听力受损耳朵中的FDL除以正常听力耳朵中的FDL）之间存在显著相关性，尽管在10例高频陡降型听力损失耳朵中的相关系数不如在10例陡降型听力损失耳朵中的高。这些结果表明DPOAE可能作为频率辨别力的客观指标。然而，应注意不要将此建议推广到所有类型的听力损失患者。
