Cluster of Excellence Hearing4all, Animal Physiology and Behavior Group, Department of Neuroscience, School of Medicine and Health Sciences, University of Oldenburg, D-26111, Oldenburg, Germany.
Cluster of Excellence Hearing4all, Animal Physiology and Behavior Group, Department of Neuroscience, School of Medicine and Health Sciences, University of Oldenburg, D-26111, Oldenburg, Germany.
Hear Res. 2019 Jun;377:142-152. doi: 10.1016/j.heares.2019.03.015. Epub 2019 Mar 21.
Informational masking (IM) is defined as the compromised ability to perceive and analyze signals from a single sound source in a cacophony of sounds from other sources even if the excitation patterns produced by these signals in the auditory periphery are well separated from those produced by the sounds from the other sources. IM that causes an elevation of discrimination thresholds is affected by the similarity between target and masker and by stimulus uncertainty. Here, six young and six elderly subjects were asked to discriminate between sequentially presented reference and target vowels of the vowel pairs /I/-/i/, /æ/-/ε/, and /α/-/Λ/. Psychometric functions were collected characterizing the discrimination of target vowels from reference vowels. Target vowels differed from the reference by one of seven steps shifting the three formants of a reference vowel towards the formants of the corresponding target vowel. Stimulus statistics were varied, generating uncertainty by non-informative but potentially distracting location, level, and fundamental frequency changes or all three combined. Young subjects tested with distracting changes applied to the target vowels only, the reference vowels only, or the target and reference vowels showed similar amounts of IM for all three conditions. Elderly subjects were tested with distracting changes applied to target vowels only. Applying uncertainty only to the target vowels led to worse vowel discrimination thresholds for young and elderly subjects and thresholds increased most for the three distracting changes combined. Elderly subjects showed higher vowel discrimination thresholds than young subjects, but the increase in vowel discrimination thresholds due to IM did not differ between young and elderly subjects. The temporal fine structure processing of elderly subjects was degraded in comparison to young subjects, but it was only correlated with the discrimination threshold for vowel pair /I/-/i/.
信息掩蔽（IM）被定义为即使这些信号在听觉外围产生的激发模式与来自其他来源的声音产生的信号很好地分开，也会在嘈杂的声音中削弱对来自单个声源的信号的感知和分析能力。导致分辨阈升高的 IM 受目标和掩蔽之间的相似性以及刺激不确定性的影响。在这里，要求 6 名年轻受试者和 6 名老年受试者辨别相继呈现的参考和目标元音对 /I/-/i/、/æ/-/ε/和 /α/-/Λ/。收集了特征描述目标元音与参考元音的辨别能力的心理物理函数。目标元音与参考元音相比，有七种变化，其中三种是将参考元音的三个共振峰移向相应目标元音的共振峰。刺激统计数据发生变化，通过非信息但可能分散注意力的位置、水平和基频变化或所有三个变化的组合产生不确定性。对仅接受目标元音、仅接受参考元音或目标和参考元音的分散变化的年轻受试者进行测试，所有三种条件下的 IM 量相似。对老年受试者仅进行目标元音的分散变化测试。仅对目标元音施加不确定性会导致年轻和老年受试者的元音辨别阈值变差，并且当三种分散变化组合时阈值增加最多。老年受试者的元音辨别阈值高于年轻受试者，但由于 IM 导致的元音辨别阈值的增加在年轻和老年受试者之间没有差异。与年轻受试者相比，老年受试者的时间精细结构处理能力下降，但仅与 /I/-/i/元音对的辨别阈值相关。
