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

听者处理语音的方式在一生中会发生变化。在早期阶段（55-65岁）更好地了解老龄化效应有助于语音技术（如助听器、语音用户界面）的进步，以更好地满足人口老龄化的需求。本文通过比较老年人和年轻人的语音感知，探讨了年龄对语音感知的影响。实验研究了听者对声音信号和语境信息的使用，并测试了听者如何适应语音中的模糊性。听众在识别语音时整合了多种声音线索。当主要的声音线索不明确时，听者可能会更多地依赖于次要线索来确保语音理解。随着老年听众经历时间处理能力的下降，他们可能通过在语音感知中更重地衡量非时间声学线索来补偿。实验1检验了先前在/b/和/p/之间的差异感知中发现的与年龄相关的线索权重转移是否延伸到/d/和/t/之间的区别。听者也可以根据输入的性质来调整他们的提示权重。实验2测试了年轻听众和年长听众使用不同的线索权重调整策略。此外，听者可以访问存储的单词信息，以帮助解决声音信号中的歧义。先前的研究发现，年长的听众比年轻的听众更多地使用这些词汇信息。实验3探讨了年轻人和老年人在学习解释歧义话语时使用词汇信息的差异。论文的最终目标是测试年轻人和老年人在如何处理说话速度的变化方面是否存在差异。在实验4中，通过在慢速和快速语音语境中嵌入/d/和/t/对比，并将这些音节呈现给年轻和年长的听者，比较他们在识别声音方面的表现，来检验语速的影响。这四个实验的结果有助于我们对人类衰老过程的理解。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.