Purpose: Recently, efforts have been made to investigate the vocal tract using magnetic resonance imaging (MRI). Due to technical limitations, teeth were omitted in many previous studies on vocal tract acoustics. However, the knowledge of how teeth influence vocal tract acoustics might be important in order to estimate the necessity of…

This study investigated the role of cross-linguistic similarity in the acquisition of Russian initial stop contrasts by Chinese learners, addressing two specific research questions: (1) How similar are Russian voiced stops to Mandarin stops for Chinese learners?; and (2) How can the speech learning model (SLM) be applied to account for the…

This dissertation investigates language-specific acoustic and aerodynamic phenomena in language contact situations. Whereas most work on second language and bilingual phonology has focused on individual consonants and vowels, this project examines patterns of coarticulation in the two languages of Spanish-English and French-English bilingual…

This dissertation explores a purportedly unusual word type known as the "sesquisyllable," which has long been considered characteristic of mainland Southeast Asian languages. Sesquisyllables are traditionally defined as "one and a half" syllables, or as one "major" syllable preceded by one "minor" syllable,…

Purpose: With the goal of using articulatory adjustments to reduce hypernasality, this study utilized an articulatory synthesis model (Childers, 2000) to simulate the adjustment of articulatory configurations with an open velopharynx to achieve the same acoustic goal as normal speech simulated with a closed velopharynx. Method: To examine the…

Speech production is inextricably linked to speech perception, yet they are usually investigated in isolation. In this study, we employed a verbal-repetition task to identify the neural substrates of speech processing with two ends active simultaneously using functional MRI. Subjects verbally repeated auditory stimuli containing an ambiguous vowel…

Working memory is believed to play a central role in almost all domains of higher cognition, yet the specific mechanisms involved in working memory are still fiercely debated. We describe a neuroimaging experiment with functional magnetic resonance imaging (fMRI) and a companion behavioral experiment, and in both we seek to adjudicate between…

This dissertation examines the relationship between the structural, phonemic properties of vowel inventories and their acoustic phonetic realization, with particular focus on the adequacy of Dispersion Theory, which maintains that inventories are structured so as to maximize perceptual contrast between their component vowels. In order to assess…

Speech perception requires the integration of information from multiple phonetic and phonological dimensions. Numerous studies have investigated the mapping between multiple acoustic-phonetic dimensions and single phonological dimensions (e.g., spectral and temporal properties of stop consonants in voicing contrasts). Many fewer studies have…

Speech utterances are more than the linear concatenation of individual phonemes or words. They are organized by prosodic structures comprising phonological units of different sizes (e.g., syllable, foot, word, and phrase) and the prominence relations among them. As the linguistic structure of spoken languages, prosody serves an important function…

Purpose: Childhood apraxia of speech (CAS) has been associated with a wide variety of diagnostic descriptions and has been shown to involve different symptoms during successive stages of development. In the present study, the authors attempted to associate the symptoms of CAS in a particular developmental stage with particular…

Models such as Eckman's markedness differential hypothesis, Flege's speech learning model, and Brown's feature-based theory of perception seek to explain and predict the relative difficulty second language (L2) learners face when acquiring new or similar sounds. In this paper, we test their predictive adequacy as concerns native English speakers'…

This paper describes a neural model of speech acquisition and production that accounts for a wide range of acoustic, kinematic, and neuroimaging data concerning the control of speech movements. The model is a neural network whose components correspond to regions of the cerebral cortex and cerebellum, including premotor, motor, auditory, and…