Meenderink Sebastiaan W F, Narins Peter M
Department of Physiological Science, University of California, Los Angeles, 621 Charles E. Young Drive South, Los Angeles, California 90095-1606, USA.
J Acoust Soc Am. 2007 Jan;121(1):344-51. doi: 10.1121/1.2382458.
When a two-tone stimulus is presented to the ear, so-called distortion product otoacoustic emissions (DPOAEs) are evoked. Adding an interference tone (IT) to these two DPOAE-evoking primaries affects normal DPOAE generation. The "effectiveness" of interference depends on the frequency of the IT in relation to the primary frequencies and this provides clues about the locus of emission generation within the inner ear. Here results are presented on the effects of ITs on DPOAEs thought to originate from the basilar papilla (BP) of a frog species. It is found that the IT always resulted in a reduction of the recorded DPOAE amplitude: DPOAE enhancement was not observed. Furthermore, iso-suppression curves (ISCs) exhibited two relative minima suggesting that the DPOAEs arise at different loci in the inner ear. These minima occurred at fixed frequencies, which coincided with those primary frequencies that resulted in maxima in DPOAE audiograms. The occurrence of two minima suggests that DPOAEs, which are presumed to originate exclusively from the BP, partially arise from the amphibian papilla as well. Finally, the finding that the minima in the ISCs are independent of the primary or DPOAE frequencies provides support for the notion that the BP functions as a single auditory filter.
当向耳朵呈现双音刺激时，会诱发所谓的畸变产物耳声发射（DPOAE）。在这两个诱发DPOAE的原始音中添加一个干扰音（IT）会影响正常DPOAE的产生。干扰的“有效性”取决于IT的频率与原始频率的关系，这为内耳中发射产生的位置提供了线索。这里展示了关于干扰音对被认为起源于一种蛙类基底乳头（BP）的DPOAE的影响的结果。发现干扰音总是导致记录的DPOAE幅度降低：未观察到DPOAE增强。此外，等抑制曲线（ISC）呈现出两个相对最小值，表明DPOAE在内耳的不同位置产生。这些最小值出现在固定频率处，这与那些在DPOAE听力图中导致最大值的原始频率一致。两个最小值的出现表明，被认为仅起源于BP的DPOAE，也部分起源于两栖乳头。最后，ISC中的最小值与原始音或DPOAE频率无关这一发现，为BP作为单一听觉滤波器的观点提供了支持。
