Purpose: Of the three currently recognized variants of primary progressive aphasia, behavioral differentiation between the nonfluent/agrammatic (nfvPPA) and logopenic (lvPPA) variants is particularly difficult. The challenge includes uncertainty regarding diagnosis of apraxia of speech, which is subsumed within criteria for variant classification.…

This dissertation presents a comprehensive instrumental acoustic analysis of phonation type distinctions in Marathi, an Indic language with numerous breathy voiced sonorants and obstruents. Important new facts about breathy voiced sonorants, which are crosslinguistically rare, are established: male and female speakers cue breathy phonation in…

Purpose: Preschool children often have difficulties in word classification, despite good speech perception and production. Some researchers suggest that they represent words using phonetic features rather than phonemes. In this study, the authors examined whether there is a progression from feature-based to phoneme-based processing across age…

This dissertation investigates the hypothesis that the more vowel-like a consonant is, the more difficult it is for listeners to classify it as geminate or singleton. A perceptual account of this observation holds that more vowel-like consonants lack clear markers to signal the beginning and ending of the consonant, so listeners don't perceive the…

Purpose: In this study, the authors aimed to investigate how listener training and the presence of intermediate acoustic cues influence transcription variability for conflicting cue speech stimuli. Method: Twenty listeners with training in transcribing disordered speech, and 26 untrained listeners, were asked to make forced-choice labeling…

Listeners hearing an ambiguous speech sound flexibly adjust their phonetic categories in accordance with lipread information telling what the phoneme should be (recalibration). Here, we tested the stability of lipread-induced recalibration over time. Listeners were exposed to an ambiguous sound halfway between /t/ and /p/ that was dubbed onto a…

A variety of studies have demonstrated that organizing stimuli into categories can affect the way the stimuli are perceived. We explore the influence of categories on perception through one such phenomenon, the perceptual magnet effect, in which discriminability between vowels is reduced near prototypical vowel sounds. We present a Bayesian model…

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…

Language acquisition may be one of the most difficult tasks that children face during development. They have to segment words from fluent speech, figure out the meanings of these words, and discover the syntactic constraints for joining them together into meaningful sentences. Over the past couple of decades, computational modeling has emerged as…

This report describes three extensions to a classification system for paediatric speech sound disorders termed the Speech Disorders Classification System (SDCS). Part I describes a classification extension to the SDCS to differentiate motor speech disorders from speech delay and to differentiate among three sub-types of motor speech disorders.…

The present study investigated the perception and production of English /w/ and /v/ by native speakers of Sinhala, German, and Dutch, with the aim of examining how their native language phonetic processing affected the acquisition of these phonemes. Subjects performed a battery of tests that assessed their identification accuracy for natural…

The present study explores the issue of the use of phonetic specificity in the process of learning new words at 20 months of age. The procedure used follows Nazzi and Gopnik [Nazzi, T., & Gopnik, A. (2001). Linguistic and cognitive abilities in infancy: When does language become a tool for categorization? "Cognition," 80, B11-B20].…

In learning to perceive and produce speech, children master complex language-specific patterns. Daunting language-specific variation is found both in the segmental domain and in the domain of prosody and intonation. This article reviews the challenges posed by results in phonetic typology and sociolinguistics for the theory of language…

The traditional phonetic classification of language rhythm as stress-timed or syllable-timed is attributed to Pike. Recently, two different proposals have been offered for describing the rhythmic structure of languages from acoustic-phonetic measurements. Ramus has suggested a metric based on the proportion of vocalic intervals and the variability…