Department of Speech-Language-Hearing Science, University of Minnesota, 164 Pillsbury Drive SE, Minneapolis, Minnesota 55455.
J Acoust Soc Am. 2010 May;127(5):3018-25. doi: 10.1121/1.3365311.
Hearing-impaired (HI) listeners often show poorer performance on psychoacoustic tasks than do normal-hearing (NH) listeners. Although some such deficits may reflect changes in suprathreshold sound processing, others may be due to stimulus audibility and the elevated absolute thresholds associated with hearing loss. Masking noise can be used to raise the thresholds of NH to equal the thresholds in quiet of HI listeners. However, such noise may have other effects, including changing peripheral response characteristics, such as the compressive input-output function of the basilar membrane in the normal cochlea. This study estimated compression behaviorally across a range of background noise levels in NH listeners at a 4 kHz signal frequency, using a growth of forward masking paradigm. For signals 5 dB or more above threshold in noise, no significant effect of broadband noise level was found on estimates of compression. This finding suggests that broadband noise does not significantly alter the compressive response of the basilar membrane to sounds that are presented well above their threshold in the noise. Similarities between the performance of HI listeners and NH listeners in threshold-equalizing noise are therefore unlikely to be due to a linearization of basilar-membrane responses to suprathreshold stimuli in the NH listeners.
听力受损（HI）的听众在心理声学任务上的表现往往不如正常听力（NH）的听众。尽管一些这样的缺陷可能反映了阈上声音处理的变化，但其他缺陷可能是由于刺激可听度和与听力损失相关的绝对阈值升高所致。掩蔽噪声可用于提高 NH 听众的阈值，使其与 HI 听众在安静环境下的阈值相等。然而，这种噪声可能会产生其他影响，包括改变外周反应特性，例如正常耳蜗基底膜的压缩输入-输出函数。本研究在 4 kHz 信号频率的 NH 听众中，使用前向掩蔽范式，在一系列背景噪声水平上，对压缩行为进行了估计。对于噪声中阈值以上 5 dB 或更高的信号，宽带噪声水平对压缩的估计没有显著影响。这一发现表明，宽带噪声不会显著改变基底膜对噪声中高于其阈值的声音的压缩反应。因此，在等阈值噪声中，HI 听众和 NH 听众的表现相似，不太可能是由于 NH 听众对阈上刺激的基底膜反应的线性化所致。
