Gaskins Casey, Jaekel Brittany N, Gordon-Salant Sandra, Goupell Matthew J, Anderson Samira
Department of Hearing and Speech Sciences, University of Maryland, College Park.
J Speech Lang Hear Res. 2019 Apr 26;62(4S):1087-1098. doi: 10.1044/2018_JSLHR-H-ASCC7-18-0133.
Purpose As pulse rate increases beyond a few hundred Hertz, younger normal-hearing (NH) participants' ability to encode temporal information in band-limited acoustic pulse trains decreases, demonstrating a rate limitation in processing rapid temporal information. Rate discrimination abilities, however, have yet to be investigated in older NH participants-a population that experiences age-related temporal processing deficits. It was hypothesized that age-related temporal processing deficits lead to decreased temporal rate discrimination abilities in older compared with younger NH participants, which could be observed in both perceptual and electrophysiological measurements. Method Fifteen younger and 15 older NH participants were presented acoustic pulse trains with a 4-kHz center frequency and 1-kHz bandwidth at 75 dB SPL monaurally. The pulse rate was 80, 200, or 400 Hz. Just noticeable differences were obtained using an adaptive procedure that instructed the participants to identify the pulse train with the highest pitch. Auditory steady-state responses (ASSRs) were recorded to the same pulse trains with 2 additional rates-20 and 40 Hz. The Digit Symbol Coding and Digit Symbol Search subtests of the Wechsler Adult Intelligence Scale ( Wechsler, 1997 ) were measured as correlates to domain-general cognitive processing speed. Results As rate increased from 80 to 400 Hz, performance on the perceptual rate discrimination task worsened in both groups. ASSR spectral energy also decreased, but only in the older group. Perceptual performance was equivalent between groups across rates. The older group had lower ASSR spectral energy (lower signal-to-noise ratios) at the 400-Hz rate than the younger group, but there were no group differences for the other rates. The overall strength of neural rate representation, along with speed of processing performance, predicted perceptual performance for the 400-Hz rate. Conclusion These results suggest that neural representation at early levels of the auditory system and processing speed are factors in perceptual auditory temporal processing performance, especially in older adults.
目的 随着脉搏率增加到几百赫兹以上，年轻的听力正常（NH）参与者在带限声脉冲序列中编码时间信息的能力会下降，这表明在处理快速时间信息时存在速率限制。然而，年龄较大的NH参与者（这一群体存在与年龄相关的时间处理缺陷）的速率辨别能力尚未得到研究。据推测，与年龄相关的时间处理缺陷会导致年龄较大的NH参与者与年轻参与者相比时间速率辨别能力下降，这在感知和电生理测量中都可以观察到。方法 向15名年轻和15名年龄较大的NH参与者单耳呈现中心频率为4 kHz、带宽为1 kHz、声压级为75 dB SPL的声脉冲序列。脉冲率为80、200或400 Hz。使用自适应程序获得刚好可察觉的差异，该程序指示参与者识别音调最高的脉冲序列。对相同的脉冲序列记录听觉稳态反应（ASSR），另外还有2个速率——20和40 Hz。测量韦氏成人智力量表（韦克斯勒，1997）的数字符号编码和数字符号搜索子测验，作为与领域通用认知处理速度的相关指标。结果 随着速率从80 Hz增加到400 Hz，两组在感知速率辨别任务上的表现都变差。ASSR频谱能量也下降，但仅在年龄较大的组中。各速率下两组的感知表现相当。年龄较大的组在400 Hz速率下的ASSR频谱能量（信噪比更低）低于年轻组，但其他速率下两组没有差异。神经速率表征的总体强度以及处理表现的速度预测了400 Hz速率下的感知表现。结论 这些结果表明，听觉系统早期水平的神经表征和处理速度是感知听觉时间处理表现的因素，尤其是在老年人中。
