Clinard Christopher G, Tremblay Kelly L, Krishnan Ananthanarayan R
Department of Speech and Hearing Sciences, University of Washington, 1417 N.E. 42nd St., Box 354875, Seattle, WA 98105, USA.
Hear Res. 2010 Jun 1;264(1-2):48-55. doi: 10.1016/j.heares.2009.11.010. Epub 2009 Nov 26.
Older adults, even with clinically normal hearing sensitivity, have auditory perceptual deficits relative to their younger counterparts. This difficulty may in part, be related to a decline in the neural representation of frequency. The purpose of this study was to examine the effect of age on behavioral and physiological measures of frequency representation. Thirty two adults (ages 22-77), with hearing thresholds 25 dB HL at octave frequencies 0.25-8.0 kHz, participated in this experiment. Frequency discrimination difference limens (FDLs) were obtained at 500 and 1000 Hz using a two-interval, two-alternative forced choice procedure. Linear regression analyses showed significant declines in FDLs at both frequencies as age increased. Frequency-following responses (FFRs) were elicited by 500 and 1000 Hz tonebursts, as well as at frequencies within and outside those FDLs. Linear regression of FFR phase coherence and FFR amplitude at frequencies at and slightly below 1000 Hz showed significant decreases as age increased. Therefore, pitch discrimination, as measured by FDLs, and neural representation of frequency, as reflected by FFR, declined as age increased. Although perception and neural representation concurrently declined, one was not predictive of the other.
老年人，即使听力敏感度在临床上正常，相对于年轻人也存在听觉感知缺陷。这种困难可能部分与频率的神经表征下降有关。本研究的目的是考察年龄对频率表征的行为和生理测量指标的影响。32名成年人（年龄在22 - 77岁之间），在倍频程频率0.25 - 8.0 kHz时听力阈值为25 dB HL，参与了本实验。使用双间隔、二选一强迫选择程序在500 Hz和1000 Hz处获得频率辨别差异阈（FDL）。线性回归分析表明，随着年龄增长，两个频率处的FDL均显著下降。由500 Hz和1000 Hz短纯音以及在那些FDL范围内和范围外的频率诱发频率跟随反应（FFR）。在1000 Hz及略低于该频率处，FFR相位相干性和FFR幅度的线性回归显示，随着年龄增长显著下降。因此，以FDL衡量的音高辨别以及以FFR反映的频率神经表征，均随着年龄增长而下降。尽管感知和神经表征同时下降，但二者之间并无预测关系。
