Martin G K, Jassir D, Stagner B B, Whitehead M L, Lonsbury-Martin B L
Department of Otolaryngology, University of Miami School of Medicine, Florida, USA.
J Acoust Soc Am. 1998 Apr;103(4):1957-71. doi: 10.1121/1.421347.
The present study used distortion-product otoacoustic emission (DPOAE) suppression tuning curves (STCs), DPOAE onset latencies (OLs), and DPOAE amplitude correlations to investigate the locus of generation of the 2f1-f2 DPOAE versus the 2f2-f1 DPOAE in humans. The results of the tuning study revealed that, for the 2f1-f2 DPOAE, the tips of the STCs tuned consistently below the geometric-mean (GM) frequency of the primary tones. In contrast, for the 2f2-f1 DPOAE, STCs tuned above the GM of the primaries, with 50% of the tip frequencies at, or above, the 2f2-f1 frequency place. When the average ratio of the 2f2-f1 to the 2f1-f2 tip frequencies was computed, a factor of 1.44 provided an estimate of the frequency shift needed to align the two DPOAE generation sites. Other results showed that OLs for the 2f2-f1 DPOAE were uniformly shorter than those for the 2f1-f2, with differences at the low frequencies amounting to as much as 6-7 ms. Further, for both DPOAEs, curves describing latency decreases as a function of increasing GM frequencies were best fit by power functions. Shifting the GM frequency producing the 2f2-f1 DPOAE by a factor of 1.6 caused the latency distributions for both DPOAEs to overlap thus resulting in a single function that described cochlear delay as a function of GM frequency. Finally, for each GM frequency in the DP-gram, sliding correlations from 108 normal ears were performed on both DPOAEs by holding the primaries producing the 2f1-f2 DPOAE constant, while all 2f2-f1 DPOAE amplitudes were successively correlated with the 2f1-f2 amplitudes. This procedure demonstrated that, for a given GM frequency producing the 2f1-f2, the correlations between the two DPOAEs peaked when the primaries of the 2f2-f1 were at a GM frequency that positioned the 2f2-f1 frequency place near the GM of the primaries that produced the 2f1-f2 DPOAE. As a whole, the above findings strongly suggest that the 2f2-f1 DPOAE in humans is generated basal to the primary-tone place on the basilar membrane.
本研究采用畸变产物耳声发射（DPOAE）抑制调谐曲线（STC）、DPOAE起始潜伏期（OL）和DPOAE幅度相关性，来研究人类中2f1 - f2 DPOAE与2f2 - f1 DPOAE的产生部位。调谐研究结果显示，对于2f1 - f2 DPOAE，STC的尖端始终调谐在初级音调的几何平均（GM）频率以下。相比之下，对于2f2 - f1 DPOAE，STC调谐在初级音调GM频率以上，50%的尖端频率处于2f2 - f1频率位置或以上。当计算2f2 - f1与2f1 - f2尖端频率的平均比值时，1.44这个因子提供了使两个DPOAE产生部位对齐所需频率偏移的估计值。其他结果表明，2f2 - f1 DPOAE的OL始终比2f1 - f2的短，低频处的差异高达6 - 7毫秒。此外，对于两种DPOAE，描述潜伏期随GM频率增加而降低的曲线最适合用幂函数拟合。将产生2f2 - f1 DPOAE的GM频率偏移1.6倍，会使两种DPOAE的潜伏期分布重叠，从而得到一个描述耳蜗延迟与GM频率关系的单一函数。最后，对于DP图中的每个GM频率，通过保持产生2f1 - f2 DPOAE的初级音调不变，对108只正常耳朵的两种DPOAE进行滑动相关性分析，同时将所有2f2 - f1 DPOAE幅度与2f1 - f2幅度依次进行相关分析。该过程表明，对于产生2f1 - f2的给定GM频率，当2f2 - f1的初级音调处于使2f2 - f1频率位置靠近产生2f1 - f2 DPOAE的初级音调GM的GM频率时，两种DPOAE之间的相关性达到峰值。总体而言，上述发现强烈表明，人类中的2f2 - f1 DPOAE是在基底膜上初级音调位置的基部产生的。
