Stefanie Shattuck-Hufnagel

Segmental durations in the vicinity of prosodic phrase boundaries

Numerous studies have indicated that prosodic phrase boundaries may be marked by a variety of acoustic phenomena including segmental lengthening. It has not been established, however, whether this lengthening is restricted to the immediate vicinity of the boundary, or if it extends over some larger region. In this study, segmental lengthening in the vicinity of prosodic boundaries is examined and found to be restricted to the rhyme of the syllable preceding the boundary. By using a normalized measure of segmental lengthening, and by compensating for differences in speaking rate, it is also shown that at least four distinct types of boundaries can be distinguished on the basis of this lengthening.

The use of prosody in syntactic disambiguation

Prosodic structure and syntactic structure are not identical; neither are they unrelated. Knowing when and how the two correspond could yield better quality speech synthesis, could aid in the disambiguation of competing syntactic hypotheses in speech understanding, and could lead to a more comprehensive view of human speech processing. In a set of experiments involving 35 pairs of phonetically similar sentences representing seven types of structural contrasts, the perceptual evidence shows that some, but not all, of the pairs can be disambiguated on the basis of prosodic differences. The phonological evidence relates the disambiguation primarily to boundary phenomena, although prominences sometimes play a role. Finally, phonetic analyses describing the attributes of these phonological markers indicate the importance of both absolute and relative measures.

A prosody tutorial for investigators of auditory sentence processing

In this tutorial we present evidence that, because syntax does not fully predict the way that spoken utterances are organized, prosody is a significant issue for studies of auditory sentence processing. We describe the basic elements and principles of current prosodic theory, review the psycholinguistic evidence that supports an active role for prosodic structure in sentence representation, and provide a road map of references that contain more complete arguments about prosodic structure and prominence. Because current theories do not predict the precise prosodic shape that a particular utterance will take, it is important to determine the prosodic choices that a speaker has made for utterances that are used in an auditory sentence processing study. To this end, we provide information about practical tools such as systems for signal display and prosodic transcription, and several caveats which we have found useful to keep in mind.

Variation in the realization of glottalization in normal speakers

Abstract Glottalized voice quality has been observed consistently in normal utterances in a variety of locations, including as an allophone of voiceless stops (in e.g., Hatfield, butler), in word-initial vowels at intonation phrase onsets and at pitch accents, and at the ends of utterances. In this study of American English, we examine glottalizations at phrase boundaries which are medial or final in an utterance. Tokens are characterized as examples of aperiodicity (irregular periods), creak (lowering of fundamental frequency with near-total damping), diplophonia (alternation in the shape, amplitude, or duration of successive periods) and a fourth category, glottal squeak. Findings include (a) a wide range in the rates of glottalization and in preferred acoustic characteristics across individual speakers, (b) a higher rate of glottalization on words at the ends of utterances than on words at the ends of utterance-medial intonational phrases, and (c) a higher rate of glottalization at the boundaries of full intonational phrases than at intermediate intonational phrases. These patterns will need to be accounted for in any comprehensive treatment of surface phonetic variation in speech.

Word-boundary-related duration patterns in English

Abstract Segments and syllables with identical distinctive feature specifications in the lexicon can be produced with strikingly different durations in different contexts, depending for example on the location of a lexical word boundary. In a study of 11 triads like tune acquire, tuna choir and tune a choir, durational differences between, e.g.,tune acquire and tuna choir occurred on either side of the word boundary in a variety of prominence contexts, broadly confirming earlier findings in the literature for a more limited set of stimuli. In general, duration measurements fortune ♯a♯choir tokens were found to be intermediate between those oftune ♯acquire and tuna♯choir, suggesting that boundaries at function words are weaker than boundaries between two content words. In addition, an investigation of the distribution of durational differences across and within syllables was conducted to evaluate five duration adjustment mechanisms proposed in the literature. Support was found for word-initial lengthening, polysyllabic shortening, accentual lengthening, and syllable ratio equalization, but not for word-final lengthening.

The role of word structure in segmental serial ordering

To test the hypothesis that similarity in position within the syllable provides an adequate description of the position constraints on segmental interaction errors in American English, five error elicitation experiments were carried out using sets of tongue-twisters based on pairs of confusable target consonants. Interaction errors increased when the two target segments shared position in the word onset, or before a stressed vowel, suggesting that these factors play an active role in the normal phonological encoding process.

Multiple targets of phrase-final lengthening in American English words

Abstract Boundary-related lengthening has been shown to affect the phrase-final word in a number of languages, but its precise distribution within the final word has not been determined. Some evidence suggests that it can begin before the final syllable (e.g. in an earlier main-stress syllable), and that it may be progressive (e.g. may affect the coda of the final syllable more than the nucleus and the nucleus more than the onset). However, only a small number of word shapes have been examined in any one language, so the available facts under-determine models of the duration adjustment process. A survey of final lengthening in words with various stress patterns in American English, using acoustic measures, shows that, in the conditions of these experiments, (a) although most of the duration increase occurs in the phrase-final syllable rime, statistically significant lengthening of 7–18% also occurs in the main-stress syllable rime, when the main stress syllable is not the final syllable, (b) this pattern is seen in both pitch-accented and unaccented final words, suggesting that it is not the result of nuclear-accent-related lengthening, (c) the distribution of lengthening across the syllables of the final word is not straightforward, in the sense that regions between the main-stress rime and the final rime appear to be skipped or lengthened less than the regions before and after them. These results suggest that the mechanism of boundary-related lengthening is more complex than current models propose; in particular, its distribution cannot be explained without reference to the location of main lexical stress and appears to involve more than one stretch of speech, at least in American English.

The representation of phonological information during speech production planning:evidence from vowel errors in spontaneous speech

A corpus of more than 500 speech errors that involve a vowel or syllabic nucleus is examined for evidence that bears on the nature of the processing representation that is in force when such errors occur. Evidence is obtained from the patterns of similarity between target segments and the intrusion segments that replace them in errors, on the assumption that target– intrusion similarity arises from characteristics of the processing representation. Findings include (1) a distinctive feature similarity between vowel targets and intrusions, (2) evidence that complex syllabic nuclei can function as error units and (3) evidence that vowel errors are constrained by lexical stress. Finally, the error patterns in both vowels and consonants, and the processing representations they suggest, are evaluated in the light of recent theoretical proposals about the phonological component of the grammar.

Question/statement judgments: an fMRI study of intonation processing.

We examined changes in fMRI BOLD signal associated with question/statement judgments in an event‐related paradigm to investigate the neural basis of processing one aspect of intonation. Subjects made judgments about digitized recordings of three types of utterances: questions with rising intonation (RQ; e.g., “She was talking to her father?”), statements with a falling intonation (FS; e.g., “She was talking to her father.”), and questions with a falling intonation and a word order change (FQ; e.g., “Was she talking to her father?”). Functional echo planar imaging (EPI) scans were collected from 11 normal subjects. There was increased BOLD activity in bilateral inferior frontal and temporal regions for RQ over either FQ or FS stimuli. The study provides data relevant to the location of regions responsive to intonationally marked illocutionary differences between questions and statements. Hum Brain Mapping 23:85–98, 2004.

THE TIMING OF SPEECH-ACCOMPANYING GESTURES WITH RESPECT TO PROSODY

The question of how and whether the body movements that accompany speaking are timed with respect to the speech has often been studied, and investigators have reached different conclusions depending on the types of gestures and aspects of prosody attended to. The ToBI system for labeling pitch accents (phrase‐level prosodic prominences) and intonational phrase boundaries, which provides a well‐defined inventory of prosodic elements, was used to label several sound files from videotaped lectures in English. A particular type of gesture, i.e., discrete sharp rapid movements that reach a perceptually salient end point, was separately labeled for syllable location in the visual display of the same lecture samples. Preliminary analysis showed a strong correlation between this type of ‘‘stroke‐like’’ gesture of the head or hands and pitch accented syllables. For example, for one speaker of Australian English, 168 of 195 strokelike gestures (86%) occurred with a pitch‐accented syllable. If these observations from coarse‐grained temporal labeling are confirmed by the frame‐by‐frame labeling now under way, it will suggest that the study of speech‐accompanying gestures can provide evidence for the prosodic structure of spoken utterances, and raise the possibility that a complete model of speech production planning should include a gestural component.