Mechanisms of accented speech recognition in native and non-native listeners: Biological insights

The goal of this study is to identify the auditory, cognitive, and linguistic processes that support foreign-accented speech recognition for native and non-native listeners. With globalization, foreign-accented speech is a regular occurrence in real-world human communication and often is a cause of miscommunication between individuals. Despite the increase in occurrence and that it is a source of communication error, little is known about how non-native speech alters the mechanisms of speech recognition. To understand the mechanisms that support accented-speech recognition and their language-dependent plasticity, 60 middle-aged adults from three different language backgrounds (native English monolingual, Spanish-English bilingual, and Mandarin-English bilingual) are tested on accented-speech recognition, the frequency-following response (FFR), and a battery of cognitive and linguistic tests. The accented-speech recognition test uses sentences of varying linguistic complexity spoken by native English monolinguals, Spanish-English bilinguals, and Mandarin-English bilinguals, allowing us to evaluate non-native speech recognition in individuals whose language backgrounds are the same or different from the talkers. The FFR is a neurophysiological response to complex auditory stimuli that provides fine-grained detail about how multifaceted, overlapping components of sound (e.g,. fundamental frequency and harmonics) are transformed into discrete neural components. Because of this, the FFR can identify how individual sound components contribute to non-native speech recognition. Additionally, to provide a complete understanding of the processes supporting recognition of non-native speech, a comprehensive battery of cognitive and linguistic processes thought to be important for non-native speech recognition are measured on these participants. Together, these tests will delineate the contribution of auditory, cognitive, and linguistic processes on foreign-accented speech recognition in native and non-native listeners. By identifying the neural mechanisms underlying accented-speech recognition and language-based plasticity of these mechanisms, this project provides the groundwork for developing strategies to assess and remediate communication problems that are common in everyday settings. Furthermore, outcomes from this project will aid in our overarching goal of delineating the shared and separate mechanisms that support all types of degraded-speech recognition and how these mechanisms are influenced by language experience. Identifying mechanisms of degraded-speech recognition and their experience dependency will contribute to the development of remediation strategies for all listeners, most notably for individuals with communication disorders, for whom speech recognition difficulties are exacerbated, such as individuals with a hearing impairment or language disorder.