Prosodic strengthening on the /s/-stop cluster and the phonetic implementation of an allophonic rule in English

AbstractThis acoustic study investigates effects of boundary and prominence on the temporal structure of s#CV and #sCV in English, and on the phonetic implementation of the allophonic rule whereby a voiceless stop after /s/ becomes unaspirated. Results obtained with acoustic temporal measures for /sCV/ sequences showed that the segments at the source of prosodic strengthening (i.e., /s/ in #sCV for boundary marking and the nucleus vowel for prominence marking) were expanded in both absolute and relational terms, whereas other durational components distant from the source (e.g., stop closure duration in #sCV) showed temporal expansion only in the absolute measure. This suggests that speakers make an extra effort to expand the very first segment and the nucleus vowel more than the rest of the sequence in order to signal the pivotal loci of the boundary vs. the prominence information. The potentially ambiguous s#CV and #sCV sequences (e.g., ice#can vs. eye#scan) were never found to be neutralized even in the phrase-internal condition, cuing the underlying syllable structures with fine phonetic detail. Most crucially, an already short lag VOT in #sCV (due to the allophonic rule) was shortened further under prosodic strengthening, which was interpreted as enhancement of the phonetic feature {voiceless unaspirated}. It was proposed that prosodic strengthening makes crucial reference to the phonetic feature system of the language and operates on a phonetic feature, including the one derived by a language-specific allophonic rule. An alternative account was also discussed in gestural terms in the framework of Articulatory Phonology

Phonetic encoding of coda voicing contrast under different focus conditions in L1 vs. L2 English

This study investigated how coda voicing contrast in English would be phonetically encoded in the temporal vs. spectral dimension of the preceding vowel (in vowel duration vs. F1/F2) by Korean L2 speakers of English, and how their L2 phonetic encoding pattern would be compared to that of native English speakers. Crucially, these questions were explored by taking into account the phonetics-prosody interface, testing effects of prominence by comparing target segments in three focus conditions (phonological focus, lexical focus, and no focus). Results showed that Korean speakers utilized the temporal dimension (vowel duration) to encode coda voicing contrast, but failed to use the spectral dimension (F1/F2), reflecting their native language experience—i.e., with a more sparsely populated vowel space in Korean, they are less sensitive to small changes in the spectral dimension, and hence fine-grained spectral cues in English are not readily accessible. Results also showed that along the temporal dimension, both the L1 and L2 speakers hyperarticulated coda voicing contrast under prominence (when phonologically or lexically focused), but hypoarticulated it in the non-prominent condition. This indicates that low-level phonetic realization and high-order information structure interact in a communicatively efficient way, regardless of the speakers’ native language background. The Korean speakers, however, used the temporal phonetic space differently from the way the native speakers did, especially showing less reduction in the no focus condition. This was also attributable to their native language experience—i.e., the Korean speakers’ use of temporal dimension is constrained in a way that is not detrimental to the preservation of coda voicing contrast, given that they failed to add additional cues along the spectral dimension. The results imply that the L2 phonetic system can be more fully illuminated through an investigation of the phonetics-prosody interface in connection with the L2 speakers’ native language experience

Prosodically conditioned strengthening and vowel-to-vowel coarticulation in English

The goal of this study is to examine how the degree of vowel-to-vowel coarticulation varies as a function of prosodic factors such as nuclear-pitch accent (accented vs. unaccented), level of prosodic boundary (Prosodic Word vs. Intermediate Phrase vs. Intonational Phrase), and position-in-prosodic-domain (initial vs. final). It is hypothesized that vowels in prosodically stronger locations (e.g., in accented syllables and at a higher prosodic boundary) are not only coarticulated less with their neighboring vowels, but they also exert a stronger influence on their neighbors. Measurements of tongue position for English /a i/ over time were obtained with Carsten’s electromagnetic articulography. Results showed that vowels in prosodically stronger locations are coarticulated less with neighboring vowels, but do not exert a stronger influence on the articulation of neighboring vowels. An examination of the relationship between coarticulation and duration revealed that (a) accent-induced coarticulatory variation cannot be attributed to a duration factor and (b) some of the data with respect to boundary effects may be accounted for by the duration factor. This suggests that to the extent that prosodically conditioned coarticulatory variation is duration-independent, there is no absolute causal relationship from duration to coarticulation. It is proposed that prosodically conditioned V-to-V coarticulatory reduction is another type of strengthening that occurs in prosodically strong locations. The prosodically driven coarticulatory patterning is taken to be part of the phonetic signatures of the hierarchically nested structure of prosody

Acoustic correlates of phrase-internal lexical boundaries in Dutch

The aim of this study was to determine if Dutch speakers reliably signal phrase-internal lexical boundaries, and if so, how. Six speakers recorded 4 pairs of phonemically identical strong-weak-strong (SWS) strings with matching syllable boundaries but mismatching intended word boundaries (e.g. reis # pastei versus reispas # tij, or more broadly C1V2(C)#C2V2(C)C3V3(C) vs. C1V2(C)C2V2(C)#C3V3(C)). An Analysis of Variance revealed 3 acoustic parameters that were significantly greater in S#WS items (C2 DURATION, RIME1 DURATION, C3 BURST AMPLITUDE) and 5 parameters that were significantly greater in the SW#S items (C2 VOT, C3 DURATION, RIME2 DURATION, RIME3 DURATION, and V2 AMPLITUDE). Additionally, center of gravity measurements suggested that the [s] to [t] coarticulation was greater in reis # pa[st]ei versus reispa[s] # [t]ij. Finally, a Logistic Regression Analysis revealed that the 3 parameters (RIME1 DURATION, RIME2 DURATION, and C3 DURATION) contributed most reliably to a S#WS versus SW#S classification

A time course of prosodic modulation in phonological inferencing: The case of Korean post-obstruent tensing.

Application of a phonological rule is often conditioned by prosodic structure, which may create a potential perceptual ambiguity, calling for phonological inferencing. Three eye-tracking experiments were conducted to examine how spoken word recognition may be modulated by the interaction between the prosodically-conditioned rule application and phonological inferencing. The rule examined was post-obstruent tensing (POT) in Korean, which changes a lax consonant into a tense after an obstruent only within a prosodic domain of Accentual Phrase (AP). Results of Experiments 1 and 2 revealed that, upon hearing a derived tense form, listeners indeed recovered its underlying (lax) form. The phonological inferencing effect, however, was observed only in the absence of its tense competitor which was acoustically matched with the auditory input. In Experiment 3, a prosodic cue to an AP boundary (which blocks POT) was created before the target using an F0 cue alone (i.e., without any temporal cues), and the phonological inferencing effect disappeared. This supports the view that phonological inferencing is modulated by listeners' online computation of prosodic structure (rather than through a low-level temporal normalization). Further analyses of the time course of eye movement suggested that the prosodic modulation effect occurred relatively later in the lexical processing. This implies that speech processing involves segmental processing in conjunction with prosodic structural analysis, and calls for further research on how prosodic information is processed along with segmental information in language-specific vs. universally applicable ways

Perceptual Cue Weighting Matters in Real-Time Integration of Acoustic Information During Spoken Word Recognition

This study investigates whether listeners’ cue weighting predicts their real-time processing of asynchronous acoustic information as the speech signal unfolds over time. It does so by testing the time course of acoustic cue integration in the processing of Seoul Korean stop contrasts by native listeners. The current study further tests whether listeners’ cue weighting is associated with cue integration at the individual level. Seoul Korean listeners’ (n = 62) perceptual weightings of voice onset time (VOT, available earlier in time) and onset fundamental frequency of the following vowel (F0, available later in time) to perceive Korean stop contrasts were measured with a speech perception task (Experiment 1), and the timing of VOT integration in lexical access was examined with a visual-world eye-tracking task (Experiment 2). The group results revealed that the timing of VOT integration is predicted by listeners’ reliance on F0, with delayed integration of VOT in target-competitor pairs where F0 is a primary cue to process the stop contrast. At the individual level, listeners who relied more on F0 than on VOT showed later integration of VOT, further elucidating the relationship between cue weighting and the time course of cue integration. These results suggest that listeners’ real-time processing of asynchronous acoustic information in lexical activation is modulated by the informativeness of perceptual cues. As such, this study provides a nuanced perspective for a better understanding of listeners’ moment-by-moment processing of acoustic information in spoken word recognition