Department of Speech, Language, and Hearing Sciences, Purdue University, West Lafayette, Indiana 47907, USA.
J Acoust Soc Am. 2018 Dec;144(6):3548. doi: 10.1121/1.5083824.
Despite clinically normal audiometric thresholds, some older adults may experience difficulty in tasks such as understanding speech in a noisy environment. One potential reason may be reduced cochlear nonlinearity. A sensitive measure of cochlear nonlinearity is two-tone suppression, which is a reduction in the auditory system's response to one tone in the presence of a second tone. Previous research has been mixed on whether suppression decreases with age in humans. Studies of efferent cochlear gain reduction also suggest that stimulus duration should be considered in measuring suppression. In the present study, suppression was first measured psychoacoustically using stimuli that were too short to result in gain reduction. The potential effect of efferent cochlear gain reduction was then measured by using longer stimuli and presenting tonal or noise precursors before the shorter stimuli. Younger adults (ages 19-22 yr) and older adults (ages 57+ yr) with clinically normal hearing were tested. Suppression estimates decreased with longer stimuli or preceding sound which included the signal frequency, but did not decrease with preceding sound at the suppressor frequency. On average, the older group had lower suppression than the younger group, but this difference was not statistically significant.
尽管临床听阈正常，但一些老年人在嘈杂环境中理解言语等任务可能会有困难。一个潜在的原因可能是耳蜗非线性度降低。耳蜗非线性度的一个敏感测量指标是两音抑制，即在第二个音存在的情况下，听觉系统对一个音的反应降低。以前关于两音抑制是否随年龄增长而降低的研究结果并不一致。关于传出性耳蜗增益降低的研究也表明，在测量抑制时应考虑刺激持续时间。在本研究中，首先使用太短而不会导致增益降低的刺激来进行心理声学测量两音抑制。然后使用更长的刺激，并在较短的刺激之前呈现音调或噪声前导，来测量传出性耳蜗增益降低的潜在影响。对具有临床正常听力的年轻成年人（19-22 岁）和老年人（57 岁及以上）进行了测试。随着更长的刺激或包含信号频率的前置声音，抑制估计值会降低，但随着抑制器频率的前置声音，抑制估计值不会降低。平均而言，老年组的抑制值低于年轻组，但这种差异无统计学意义。
