Abdala C
House Ear Institute, Children's Auditory Research and Evaluation Center, Los Angeles, California 90057, USA.
J Acoust Soc Am. 2001 Dec;110(6):3155-62. doi: 10.1121/1.1417523.
Previous work has shown that distortion product otoacoustic emission (DPOAE) suppression tuning curves (STCs) recorded from premature neonates are narrower than adult STCs at both low and high frequencies. This has been interpreted to indicate an immaturity in cochlear function prior to term birth. However, an alternative explanation for this finding is that adult DPOAE STCs are broadened and reflect cochlear hair cell loss in normal-hearing adults due to aging, and natural exposure to noise and ototoxins. This alternative hypothesis can be tested by studying suppression tuning in normal-hearing school-aged children. If normal-hearing children, who have not aged significantly or been exposed to noise/ototoxins, have DPOAE suppression tuning similar to adults, the auditory aging hypothesis can be ruled out. However, if children have tuning similar to premature neonates and dissimilar from adults, it implicates aging or other factors intrinsic to the adult cochlea. DPOAE STCs were recorded at 1500, 3000, and 6000 Hz using optimal parameters in normal-hearing children and adults. DPOAE STCs collected previously from premature neonates were used for age comparisons. In general, results indicate that tuning curves from children are comparable to adult STCs and significantly different from neonatal STCS at 1500 and 6000 Hz. Only the growth of suppression was not adultlike in children and only at 6000 Hz. These findings do not strongly support the auditory aging hypothesis as a primary explanation for previously observed neonatal-adult differences in DPOAE suppression tuning. It suggests that these age differences are most likely due to immaturities in the neonatal cochlea. However, nonadultlike suppression growth observed in children at 6000 Hz warrants further attention and may be indicative of subtle alternations in the adult cochlea at high frequencies.
先前的研究表明，从早产新生儿记录的畸变产物耳声发射（DPOAE）抑制调谐曲线（STC）在低频和高频时都比成人的STC更窄。这被解释为表明足月出生前耳蜗功能不成熟。然而，这一发现的另一种解释是，成人DPOAE STC变宽，反映了正常听力成人由于衰老、自然暴露于噪声和耳毒性药物导致的耳蜗毛细胞损失。这个替代假设可以通过研究正常听力学龄儿童的抑制调谐来检验。如果没有明显衰老或暴露于噪声/耳毒性药物的正常听力儿童具有与成人相似的DPOAE抑制调谐，则可以排除听觉衰老假说。然而，如果儿童的调谐与早产新生儿相似且与成人不同，则意味着衰老或成人耳蜗固有的其他因素。使用最佳参数在正常听力儿童和成人中记录了1500、3000和6000 Hz的DPOAE STC。先前从早产新生儿收集的DPOAE STC用于年龄比较。总体而言，结果表明，儿童的调谐曲线与成人STC相当，在1500和6000 Hz时与新生儿STC有显著差异。只有抑制的增长在儿童中不像成人，且仅在6000 Hz时如此。这些发现并不强烈支持听觉衰老假说作为先前观察到的新生儿与成人在DPOAE抑制调谐方面差异的主要解释。这表明这些年龄差异很可能是由于新生儿耳蜗不成熟所致。然而，在6000 Hz时儿童中观察到的非成人样抑制增长值得进一步关注，可能表明成人耳蜗在高频时有细微变化。
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