Doctoral Dissertation Research: Speech perception in younger and older adults: Cue-weighting and contextual information

在人的一生中，听者处理语音的方式会发生变化。更好地了解老龄化的早期阶段(55-65岁)有助于语音技术(如助听器、语音用户界面)的进步，以更好地满足老龄化人口的需求。本论文通过比较老年人和年轻人的言语知觉来考察衰老对言语知觉的影响。这些实验调查了听者对声音信号和语境信息的使用情况，并测试了听者如何适应语音中的歧义。听者在识别语音时集成了多个声学提示。当主要的声学提示是模棱两可的时，听者可能更多地依赖次要提示来确保语音理解。随着年长的听者感受到时间处理能力的降低，他们可能会通过在语音感知中更重地权衡非时间声学线索来进行补偿。实验一测试了之前在/b/和/p/之间的差异知觉中发现的与年龄相关的线索-权重转移是否延伸到/d/vs./t/区分。听众还可以根据输入的性质调整其提示权重。实验二测试了年轻听者和年长听者是否使用不同的线索权重调整策略。此外，收听者可以访问存储的关于单词的信息，以帮助解决声音信号中的歧义。先前发现，年长的听者比年轻的听者在更大程度上使用这种词汇信息。实验3探讨了年轻人和老年人在学习理解含糊的话语时对词汇信息的使用是否存在差异。这篇论文的最后一个目标是测试年轻人和老年人在处理语速变化方面是否存在差异。在实验4中，通过在慢速和快速语境中嵌入/d/vs./t/对比，并将这些音节呈现给年轻和年长的听者来比较他们在识别声音方面的表现，从而检验了语速的效果。这四个实验的结果有助于我们对人类衰老过程的理解。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The way listeners process speech sounds changes across the lifespan. A better understanding of the aging effect in its early stage (55-65 years old) contributes to the advancement of speech technology (e.g., hearing aids, voice user interfaces) to better fulfill the needs of an aging population. This dissertation investigates the influence of aging on speech perception by comparing speech perception in older vs. younger adults. The experiments investigate listeners’ use of the acoustic signal and contextual information, and test how listeners adapt to ambiguity in speech sounds. Listeners integrate multiple acoustic cues when identifying speech sounds. When the primary acoustic cue is ambiguous, listeners may rely more heavily on a secondary cue to ensure speech understanding. As older listeners experience reduced temporal processing abilities, it is possible that they compensate by weighing non-temporal acoustic cues more heavily in speech perception. Experiment 1 tests whether the age-related cue-weighting shift found previously in the perception of the difference between /b/ and /p/ extends to the /d/ vs. /t/ distinction. Listeners may also adjust their cue weighting depending on the nature of the input. Experiment 2 tests whether younger and older listeners use different cue-weighting adjustment strategies. Additionally, listeners may access stored information about words to help resolve ambiguities in the acoustic signal. Older listeners were previously found to use this lexical information to a greater degree than younger listeners. Experiment 3 explores whether younger and older adults differ in their use of lexical information when learning to interpret utterances that are ambiguous. A final goal of the dissertation is to test whether younger and older adults differ in how they handle changes in speaking rate. In Experiment 4, the effect of speaking rate is examined by embedding /d/ vs. /t/ contrasts in slow and fast speech contexts and presenting these syllables to younger and older listeners to compare their performance in identifying the sounds. The results of the four experiments contribute to our understanding of the human aging process.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.