Cynthia Girand

Effects of disfluencies, predictability, and utterance position on word form variation in English conversation

Function words, especially frequently occurring ones such as (the, that, and, and of), vary widely in pronunciation. Understanding this variation is essential both for cognitive modeling of lexical production and for computer speech recognition and synthesis. This study investigates which factors affect the forms of function words, especially whether they have a fuller pronunciation (e.g., thi, thaet, aend, inverted-v v) or a more reduced or lenited pronunciation (e.g., thax, thixt, n, ax). It is based on over 8000 occurrences of the ten most frequent English function words in a 4-h sample from conversations from the Switchboard corpus. Ordinary linear and logistic regression models were used to examine variation in the length of the words, in the form of their vowel (basic, full, or reduced), and whether final obstruents were present or not. For all these measures, after controlling for segmental context, rate of speech, and other important factors, there are strong independent effects that made high-frequency monosyllabic function words more likely to be longer or have a fuller form (1) when neighboring disfluencies (such as filled pauses uh and um) indicate that the speaker was encountering problems in planning the utterance; (2) when the word is unexpected, i.e., less predictable in context; (3) when the word is either utterance initial or utterance final. Looking at the phenomenon in a different way, frequent function words are more likely to be shorter and to have less-full forms in fluent speech, in predictable positions or multiword collocations, and utterance internally. Also considered are other factors such as sex (women are more likely to use fuller forms, even after controlling for rate of speech, for example), and some of the differences among the ten function words in their response to the factors.

Distinguishing Deceptive from Non-Deceptive Speech

To date, studies of deceptive speech have largely been confined to descriptive studies and observations from subjects, researchers, or practitioners, with few empirical studies of the specific lexical or acoustic/prosodic features which may characterize deceptive speech. We present results from a study seeking to distinguish deceptive from non-deceptive speech using machine learning techniques on features extracted from a large corpus of deceptive and non-deceptive speech. This corpus employs an interview paradigm that includes subject reports of truth vs. lie at multiple temporal scales. We present current results comparing the performance of acoustic/prosodic, lexical, and speaker-dependent features and discuss future research directions.

Form and function of intonational phrase heads

This study examines the phonetic and phonological features essential to the investigation of the internal structure of the intonational phrase. This is crucial for identifying and explaining the forms and functions of basic intonational units. There are two primary intonational contour modeling theories [Ladd (1983) and references therein]. One suggests that phrasal contours are the basic units of intonation. Within this theory, contour shapes are associated with particular functions or meanings. In contrast, a more recent theory claims that individual tones (i.e., abstract phonological units) are the basic units of intonation, and intonational contours result from the concatenation of adjacent tones in a phrase. Using 756 utterances from the Switchboard and Buckeye corpora, the present study takes a closer look at the basic units that compose the intonational contour. While the nucleus has long been identified as a functionally important part of an intonational phrase, the head of an intonational phrase ...

Positional and planning effects on the durational structure of repetition strings

Gaining time to resolve some difficulty in the production of upcoming speech is the primary function of unplanned repetitions. Understanding their duration structure is thus crucial to modeling their production, which surely differs greatly from fluent phrases. When the duration structure of the entire repetition string of unplanned repetitions is examined, strong global dependencies are found. Repetition strings are words/phrases repeated once or more, together with silent and filled pauses optionally occurring next to them. The main effects are that durations of first and second string items, whether repeated words or pauses, are positively correlated with the duration of the rest of the string; items, whether words or pauses, are shorter as they occur later in the string; and strings that begin with a pause average longer than strings that do not. The study is based on an analysis of 503 disfluent repetitions taken from the ICSI phonetically transcribed sample of the Switchboard conversation corpus, ex...

The structure of repetition strings in the Switchboard corpus

An investigation of reduction in the ten most frequent English function words in Switchboard, to be presented at ICSLP’98, found that repetition or following silence or filled pause, which were taken as symptoms of planning problems, were strongly associated with longer durations and lack of reduction, extending earlier results for the definite article [J. E. Foxtree and H. H. Clark, Cog. 62, 151–167 (1997)]. As a followup to this study, the structure of unplanned repetition strings is examined more closely. The study is based on an analysis of the lexical transcriptions of the repetitions of words and short phrases from over 100 h of recorded conversations from the Switchboard corpus. Detailed information about the phonetic form and contexts of repetitions a retaken from a phonetically transcribed sample of 4 h of conversation [S. Greenberg et al., ICSLP 96 Proc. (1996)]. Repetitions are overwhelmingly unplanned; are overwhelmingly function words; and are mostly single repetitions of words, although comp...