The interplay between prosodic prominence and boundary strength in the production of English checked steady-state vowels

Immediate integration of different types of prosodic information during on-line spoken language comprehension: An ERP study

Many phonological processes can be affected by segmental context spanning word boundaries, which often lead to variable outcomes. This paper tests the idea that some of this variability can be explained by reference to production planning. We examine coronal stop deletion (CSD), a variable process conditioned by preceding and upcoming phonological context, in a corpus of spontaneous British English speech, as a means of investigating a number of variables associated with planning: Prosodic boundary strength, word frequency, conditional probability of the following word, and speech rate. From the perspective of production planning, (1) prosodic boundaries should affect deletion rate independently of following context; (2) given the locality of production planning, the effect of the following context should decrease at stronger prosodic boundaries; and (3) other factors affecting planning scope should modulate the effect of upcoming phonological material above and beyond the modulating effect of prosodic boundaries. We build a statistical model of CSD realization, using pause length as a quantitative proxy for boundary strength, and find support for these predictions. These findings are compatible with the hypothesis that the locality of production planning constrains variability in speech production, and have practical implications for work on CSD and other variable processes.

We examined how well prosodic boundary strength can be captured by two declination stylization methods as well as by four different representations of pitch register. In the stylization proposed by Liebermann et al. (1985) base- and topline are fitted to peaks and valleys of the pitch contour, whereas in Reichel&Mady (2013) these lines are fitted to medians below and above certain pitch percentiles. From each of the stylizations four feature pools were induced representing different aspects of register discontinuity at word boundaries: discontinuities related to the base-, mid-, and topline, as well as to the range between base- and topline. Concerning stylization the median-based fitting approach turned out to be more robust with respect to declination line crossing errors and yielded base-, topline and range-related discontinuity characteristics with higher correlations to perceived boundary strength. Concerning register representation, for the peak/valley fitting approach the base- and topline patterns showed weaker correspondences to boundary strength than the other feature pools. We furthermore trained generalized linear regression models for boundary strength prediction on each feature pool. It turned out that neither the stylization method nor the register representation had a significant influence on the overall good prediction performance.

A recent study (Kim & Cho, 2013, The Journal of the Acoustical Society of America) reported that the perception of a prosodic boundary leads to a shift in a stop-identification function in English, so that stops with a relatively long VOT are accepted as voiced if occurring after a major prosodic boundary. Even Korean learners of English showed such a shift. This shift would seem to result from compensation for post-boundary lengthening effects (or domain-initial strengthening) and thereby help to overcome the invariance problem in speech perception. In two experiments, we ask how this effect comes about. The first experiment tested whether a simple adjustment to a change in overall speaking rate would be sufficient to account for the shift. Results showed that while the global speaking-rate change modulates phonetic categorization in a similar way as a change in the prosodic boundary strength, the speaking-rate effect is not sufficient to explain the boundary effect. That is, there was a more robust shift in a stop identification function with localized slowing down of the final syllable due to an intonational phrase (IP) boundary than with global slowing down of speaking rate. The second experiment therefore investigated the contribution of an F0 cue to the observed perceptual shift and found that the presence or absence of the F0 cue did not mediate the effect of prosodic boundaries on phonetic categorization. This suggests that a perception shift in phonetic categorization stems primarily from the listeners’ adjustment to temporal variation, though its source is different from the speaking rate. The results are considered in terms of two possible accounts: one that takes both the boundary-induced and the speaking rate-induced effects as listeners’ adjustments to low-level temporal variation, and the other that separates them by taking the boundary-induced effects to arise with computation of higher-level prosodic structure, given that the source of the localized slowing down effect is a prosodic boundary.

Previous laboratory studies have shown that prosodic structures are encoded in the modulations of phonetic patterns of speech including suprasegmental as well as segmental features. In particular, effects of prosodic context on duration and intensity of syllables and words have been widely reported. Drawing on prosodically annotated large-scale speech data from the Buckeye corpus of conversational speech of American English, the current study attempted to examine whether and how prosodic prominence and phrase boundary of everyday conversational speech, as determined by a large group of ordinary listeners, are related to the phonetic realization of duration and intensity. The results showed that the patterns of word durations and intensities are influenced by prosodic structure. Closer examinations revealed, however, that the effects of prosodic prominence are not the same as those of prosodic phrase boundary. With regard to intensity measures, the results revealed the systematic changes in the patterns of overall RMS intensity near prosodic phrase boundary but the prominence effects are restricted to the nucleus. In terms of duration measures, both prosodic prominence and phrase boundary are the most closely related to the lengthening of the nucleus. Yet, prosodic prominence is more closely related to the lengthening of the onset while phrase boundary lengthens the coda duration more. The findings from the current study suggest that the phonetic realizations of prosodic prominence are different from those of prosodic phrase boundary, and speakers signal different prosodic structures through deliberate modulations of the internal phonetic structure of words and listeners attend to such phonetic variations.

Background/Aims: In French, the size of a focus constituent is not reliably marked through pitch accent assignment as in many stress accent languages. While it has been argued that the distribution of lower-level prosodic boundaries plays a role, this is at best a weak cue to focus, leaving open the question of whether other marking strategies are available. In this study, we assess whether the right edge of a contrastive focus constituent is marked by differences in prosodic boundary strength. Methods: We elicited utterances with target words in six combinations of focus and syntactic contexts using an interactive production task. Results: The results show that if a given location is realized as an accentual phrase boundary in an all-focus context, then it is realized as an intermediate phrase boundary when it coincides with the right edge of a narrow-focus constituent. A location that is an intermediate phrase boundary in an all-focus context, however, remains unchanged under narrow focus. Conclusion: These findings suggest that focus constituents are constrained to align with a minimum prosodic domain size in French (i.e., the intermediate phrase), and that French does not rely on a general strategy of prosodic enhancement for marking focus.

This study addresses the questions how to parameterize (1) aspects of fundamental frequency (F0) register, i.e. time-varying F0 level and range within prosodic phrases and (2) F0 discontinuities at prosodic boundaries in order to predict perceived prosodic boundary strength in Hungarian spontaneous speech. For F0 register stylization we propose a new fitting procedure for base-, mid-, and toplines that does not require error-prone local peak and valley detection and is robust against disturbing influences of high pitch accents and boundary tones. From these linear stylizations we extracted features which reflect F0 boundary discontinuities and fitted stepwise linear regression and regression tree models to predict perceived boundary strength. In a ten-fold cross-validation the mean correlation between predictions and human judgments amounts up to 0.8.

This paper proposes a new methodology for automatically comparing the speech rhythm structure of two utterances. Eleven parameters were automatically extracted from 44 pairs of audiofiles yielding 11-size difference vectors. The parameters include speech rate, duration-related stress group rate, prominence and prosodic boundary strength, f0 peak rate, as well as the coupling strength between underlying syllable and stress group oscillators. The 11-parameter difference vectors were used to infer the perceptual differences identified by a group of 10 listeners who judged the same 44 pairs of audiofiles . The results indicate that duration-related prominence or prosodic boundary rate and speech rate, taken together, predict up to 71 % of the response variance. To a minor extent, prominence/boundary strength mean and non-prominent VV unit rate predict up to 60 % of the response variance when combined with prominence or prosodic boundary rate.Keywordsspeech rhythmprominencerhythm perceptionspeech rate

The distribution of preboundary lengthening within the phrase-final word is controversial. In CV syllables immediately preceding a prosodic boundary, the acoustic duration of the syllable onset C is less involved than that of the following rime V in the lengthening phenomenon. Moreover, preboundary lengthening might be extended to the stressed/accented rime within the phrase final word. On the other hand, articulatory constriction gesture for the onset consonant can be lengthened despite not being immediately adjacent to a boundary. In this study, we explore the effects of prosodic boundary and prominence in Italian, at both acoustic and articulatory level. Bilabial consonants in CV onset position were examined. The consonants were inserted in unstressed (word final) and stressed (penultimate vs. antepenultimate) syllables occurring in the vicinity of prosodic boundaries of different levels. In final syllables, the acoustic duration of the onset consonant was not affected by the prosodic boundary manipulation whereas the closing gesture duration showed a pattern of lengthening which was stronger for higher level prosodic boundaries. In non-final syllables, no acoustic/articulatory effect was found for onset consonants but only on the stressed vowels in penultimate position. Structural, phonological and phonetic constraints might be at work in determining preboundary lengthening.

In this study the effects of accent and prosodic boundaries on the production of English vowels (/a,i/), by concurrently examining acoustic vowel formants and articulatory maxima of the tongue, jaw, and lips obtained with EMA (Electromagnetic Articulography) are investigated. The results demonstrate that prosodic strengthening (due to accent and/or prosodic boundaries) has differential effects depending on the source of prominence (in accented syllables versus at edges of prosodic domains; domain initially versus domain finally). The results are interpreted in terms of how the prosodic strengthening is related to phonetic realization of vowel features. For example, when accented, /i/ was fronter in both acoustic and articulatory vowel spaces (enhancing [-back]), accompanied by an increase in both lip and jaw openings (enhancing sonority). By contrast, at edges of prosodic domains (especially domain-finally), /i/ was not necessarily fronter, but higher (enhancing [+high]), accompanied by an increase only in the lip (not jaw) opening. This suggests that the two aspects of prosodic structure (accent versus boundary) are differentiated by distinct phonetic patterns. Further, it implies that prosodic strengthening, though manifested in fine-grained phonetic details, is not simply a low-level phonetic event but a complex linguistic phenomenon, closely linked to the enhancement of phonological features and positional strength that may license phonological contrasts.

This paper highlights a hitherto unreported change in progress among northern speakers of British English, with increasing post-nasal [ɡ]-presence in words like sing or wrong pre-pausally. The factors that condition this innovation are unclear due to collinearity between various boundary phenomena. The right edge of phrasal prosodic categories may be associated with boundary tones, final lengthening, and pause; consequently, the variable presence of [ɡ] appears to be affected by prosodic boundary strength, segmental duration, and the presence and duration of a following pause. These factors are teased apart through analysis of an elicitation task from 30 northern speakers, which reveals that [ŋɡ] clusters are conditioned most strongly by pause. Post-nasal [ɡ]-presence is only licensed when the following consonant-initial word is temporally distant, showing only minimal sensitivity to prosodic boundaries directly. The surface effect of segmental duration arises only indirectly through its collinearity with pause duration. Current theoretical approaches to external sandhi emphasize a range of different factors, including phonological representations of prosodic constituency, phonetic parameters like segmental duration, and psycholinguistic mechanisms of production planning. This paper provides quantitative evidence from an under-reported feature of northern English that bears directly on these debates.

Prosodic boundary strength: An articulatory and perceptual study

The durational effects of prosodic boundaries and prosodic prominence are well known, but their interaction is less well-understood. Recent studies in English [Turk and Shattuck-Hufnagel (2007); Byrd and Riggs (2008)] indicate that the two effects might be interdependent. Two acoustic experiments are presented, examining the role of boundary- and prominence-related lengthening and their interaction in Greek. The first experiment explores the effects of boundary-adjacent lengthening (conditions: no boundary, intermediate phrase, intonational phrase) and prominence (on the first, second, and third syllable away from the boundary). The second experiment examines these same effects, but post-boundary. Data from eight speakers were collected. The results from five speakers are presented. Results show that pre-boundary, both prominence and boundary have an effect on segment duration. Two prosodic levels (the level of word and one higher level) are distinguished. Furthermore, for two speakers, there is an interaction effect, such that three prosodic levels are distinguished when the prominent syllable is boundary-adjacent. The post-boundary condition shows less systematic results, with different speakers exhibiting different patterns. These results suggest that prosodic effects are speaker dependent, more stable pre-boundary, and that prominence and boundaries interact, increasing prosodic boundary marking. Implications for models of prosodic structure are discussed.

Acoustic data are presented from a prosodic database containing data from 3 French speakers. The prosodic boundaries examined are the Utterance, the Intonational Phrase, the Accentual Phrase, and the Word. The aim is to study the interaction of coarticulatory effects with prosodic effects. The vowel /a/ before the prosodic boundary and the consonants /b d f s / after the prosodic boundary are examined. It is found that the vowel duration is greatly affected by the strength of the prosodic boundary, but consonant duration less so. The duration of the fricative consonants is more stable than the stop consonants. Formant values suggest that /a/ is lower and more back the stronger the prosodic boundary, and that the vowel is more likely to r each its low target following a bilabial consonant /b f/. Based on an examination of formant values, the velar stop / / appears to have much variability in the front-back dimension. Finally, there is a strong negative correlation between duration and mean velocity of the formant transition, and this effect is strongly related to the strength of the prosodic boundary.

Phrase-final syllable duration and pauses are generally considered to be positively correlated: The stronger the boundary, the longer the duration of phrase-final syllables, and the more likely or longer a pause. Exploring a large sample of complex literary prose texts read aloud, we examined pause likelihood and duration, pre-boundary syllable duration, and the pitch excursion at prosodic boundaries. Comparing these features across six predicted levels of boundary strength (level 0: no break; 1: simple phrase break; 2: short comma phrase break; 3: long comma phrase break; 4: sentence boundary; 5: direct speech boundary), we find that they are not correlated in a simple monotonic fashion. Whereas pause duration monotonically increases with boundary strength, both pre-boundary syllable duration and the pitch excursion on the pre-boundary syllable are largest for level-2 breaks and decrease significantly through levels 3 to 5. Our analysis suggests that pre-boundary syllable duration is partly contingent on the tonal realization, which is subject to f0 declination as the utterance progresses. We also surmise that pre-boundary syllable duration reflects differences in planning complexity for the different prosodic and syntactic boundaries. Overall, this study shows that a simple monotonic correlation between pause duration and pre-boundary syllable duration is not valid.