Doctoral Dissertation Research: Production and perception of native and non-native speech enhancement

为了成功地进行言语交流，说话者必须能够将他们的信息清楚地传达给他们的听众。例如，当听者第一次听不懂说话者所说的话时，说话者可能会以更清晰的方式重复他们所说的话，以便听者能够理解。这种为听者提高语音可理解性的看似简单的动作通常是由流利的语言使用者自然地执行的，然而对于产生不那么流利和不那么可理解的语音的人，例如非母语使用者来说，这可能是困难的。不被听众理解会对非母语人士产生非常实际的后果，因为这会大大减少他们获得工作和教育的机会，更广泛地说，这会减少他们作为平等成员参与社会的机会。这一问题的重要性在美国非英语母语者不断增长的人口中突显出来。该项目试图通过研究不同语言背景的说话者如何在不同的交流环境中使用语音增强策略来更好地理解为什么在非母语环境下提高语音清晰度是困难的。这一项目的结果可以为第二语言学习方法的发展以及对可能难以提高语言清晰度的临床人群的干预提供参考。这个项目的目标是了解两个方面的因素：说话人使用什么策略来提高他们的演讲能力，以及这些策略是如何被听者感知的。具体地说，这些实验考察了不同来源对说话人清晰说话能力的影响，例如说话人的语言背景、演讲材料的特征(例如，对单词或短语的熟悉程度)以及交际语境的特征。此外，该项目还考察了说话者提高语音可理解性的尝试如何转化为听者对该演讲的感知，包括感知的可理解性程度(理解演讲的难易程度)和感知的说话者努力程度(说话者试图说得清楚的程度)。这个项目将帮助我们更好地了解说话者和听话者在提高各种母语和非母语人群的语音可理解性方面的贡献。该奖项反映了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。

In order for speech communication to be successful speakers must be able to deliver their messages clearly to their listeners. For example, when a listener does not understand what was said by a speaker the first time, the speaker may repeat what they said in a clearer manner so that the listener can understand it. This seemingly simple act of enhancing intelligibility of speech for a listener is often carried out naturally by fluent speakers of the language, yet it can be difficult for people who produce less fluent and less intelligible speech, such as non-native speakers of the language. Not being understood by listeners has very real consequences for non-native speakers as it can significantly decrease their opportunities to obtain jobs and education, and more broadly, to participate in society as an equal member. The significance of this issue is highlighted by the growing population of non-native English speakers in the U.S. This project seeks to better understand why it can be difficult to enhance speech intelligibility in a non-native language by examining how speakers of different linguistic backgrounds use speech enhancement strategies in different communication contexts. The results of this project could inform the development of methodologies for second language learning as well as interventions for clinical populations who may experience difficulty enhancing their speech intelligibility. The goal of this project is to understand two aspects of what contributes to enhancing speech intelligibility: what kinds of strategies speakers use to enhance their speech and how these strategies are perceived by listeners. Specifically, the proposed experiments examine how a speaker’s ability to speak clearly is affected by different sources, such as the speaker's language background, characteristics of the speech materials (e.g., familiarity of the words or phrases), and characteristics of the communication context. Further, the project examines how speakers' attempts to enhance speech intelligibility translate to listeners' perception of this speech, including perceived degree of comprehensibility (how easy it is to understand the speech) and perceived degree of speaker effort (how hard the speaker is trying to speak clearly). This project will help us better understand the contributions from both speakers and listeners to enhancing speech intelligibility for a variety of native and non-native speaking populations.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.