Frisina D R, Frisina R D
International Center for Hearing and Speech Research, Rochester Institute of Technology, NY 14623-0887, USA.
Hear Res. 1997 Apr;106(1-2):95-104. doi: 10.1016/s0378-5955(97)00006-3.
This study is part of ongoing efforts to characterize and determine the neural bases of presbycusis. These efforts utilize humans and animals in sets of overlapping hypotheses and experiments. Here, 50 young adult and elderly subjects, with normal audiometric thresholds or high-frequency hearing loss, were presented three types of linguistic materials at suprathreshold levels to determine speech recognition performance in noise. The study sought to determine how peripheral and central auditory system dysfunctions might be implicated in the speech recognition problems of elderly humans. There were four main findings. (1) Peripheral auditory nervous system pathologies, manifested as reduced sensitivity for speech-frequency pure tones and speech materials, contribute to elevated speech reception thresholds in quiet, and to reduced speech recognition in noise. (2) Good cognitive ability was demonstrated in the old subjects who took advantage of supportive context as well or better than young subjects, strongly indicating that the cortical portions of the speech/language nervous system did not account for the speech understanding dysfunctions of the old subjects. (3) When audibility and cognitive functioning were not affected, the demonstrated speech-recognition in-noise dysfunction remained in old subjects. This implicates auditory brainstem or auditory cortex temporal-resolution dysfunctions in accounting for the observed differences in speech processing. (4) Performance differences between young and elderly subjects with elevated thresholds illustrate the effects of age plus hearing loss and thereby implicate both peripheral and central dysfunctions in presbycusics. This is because the differences in performance between young and elderly subjects with normal peripheral sensitivity identified a central auditory dysfunction.
本研究是确定老年性聋特征及神经基础的持续努力的一部分。这些努力在一系列相互重叠的假设和实验中利用了人类和动物。在此，50名听力阈值正常或有高频听力损失的年轻和老年受试者，在阈上水平被呈现三种类型的语言材料，以确定噪声环境下的语音识别表现。该研究旨在确定外周和中枢听觉系统功能障碍如何与老年人的语音识别问题相关。有四个主要发现。（1）外周听觉神经系统病变，表现为对语音频率纯音和语音材料的敏感性降低，导致安静环境下言语接受阈值升高，以及噪声环境下语音识别能力下降。（2）老年受试者若能利用支持性语境，其认知能力表现良好，且与年轻受试者相当或更好，这有力表明言语/语言神经系统的皮质部分并非老年受试者言语理解功能障碍的原因。（3）当可听度和认知功能未受影响时，老年受试者在噪声中的语音识别功能障碍依然存在。这意味着听觉脑干或听觉皮层的时间分辨率功能障碍是导致观察到的语音处理差异的原因。（4）阈值升高的年轻和老年受试者之间的表现差异说明了年龄加听力损失的影响，从而表明老年性聋中外周和中枢功能障碍均有涉及。这是因为外周敏感性正常的年轻和老年受试者之间的表现差异表明存在中枢听觉功能障碍。
