Prosodic Strengthening Research Articles

The encoding of prominence relations in supra-laryngeal articulation across speaking styles

Speakers modify their supra-laryngeal articulation on the one hand as a function of prosodic prominence and on the other hand as a function of speaking style. Articulatory movements are spatio-temporally expanded in words that are highlighted due to prosodic strengthening, but also in utterances that are produced in a loud speaking style. What remains unclear, to date, is how these two phenomena interact, or, in other words, how prominence relations are encoded in loud speech. In this paper, we use electromagnetic articulography to investigate lip and tongue kinematics and analyze selected acoustic parameters across several focus conditions in habitual and loud speech. Prosodic prominence relations are studied as the simultaneous strengthening of highlighted words and the attenuation of words in the background. The results show that prominence relations can be encoded multidimensionally in loud speech. Some modifications are even stronger in loud speech than in habitual speech, despite the general articulatory modifications associated with a loud speaking style. In both speaking styles, the attenuation of words in the background tends to be more robust than the strengthening of highlighted words. The paper underlines the flexibility of the multidimensional phonetic space in the encoding of prosodic prominence across varying communicative demands.

Voice quality distinctions of the three-way stop contrast under prosodic strengthening in Korean*

Voice quality distinctions of the three-way stop contrast under prosodic strengthening in Korean*

Prosodic realization of identification and contrastive focus in Korean multiple accusative constructions

This study investigated how two different kinds of prominence-induced prosodic strengthening, identificational focus and contrastive focus, are phonetically realized in Seoul Korean. In the experiment, 16 native speakers produced target sentences presented in three different prosodic conditions: default reading, NP1-contrast, and NP2-contrast. The production data presented three crucial characteristics in the phonetic manifestations of prominence-induced prosodic strengthening in Seoul Korean. First, identificational focus gave rise to temporal expansion and pitch enhancement over the constructions under the focus. Second, contrastive focus brought about modification of temporal, pitch, and prosodic structures as well as pre- and post-focus compression. Finally, the two different types of prominence marking interacted with each other; the prosodic realization of contrastive focus overrode the prosodic realization of identificational focus, which was in line with the formal (syntactic) distinction of the two types of focus. To conclude, the current study demonstrates the interplay of information structure and discourse contexts in prosodic strengthening effects induced by prominence, especially in Seoul Korean, which lacks lexical stress and pitch accent.

Competing prosodic influences on VOT length in Hawaiian

Previous research on voice onset time shows that VOT in unaspirated stops is at best only weakly affected by prosodic strengthening (Hodgson, 2021; Simonet et al., 2014). VOT duration is analyzed in Hawaiian, which has only /p k/, in conjunction with a prosodic analysis, to determine its stop type, and investigate whether prosodic boundaries condition VOT length. Data comprise speech from seven speakers interviewed on the radio program Ka Leo Hawai‘i in the 1970–80s (Kettig, 2021). Using the computational prosodic grammar in Parker Jones (2010), stops were coded for whether they occurred in lexical word-initial/medial position, in a stressed/unstressed syllable, and in prosodic word-initial/medial position. The results indicate that the average duration of /p/ is 24ms and /k/ is 41ms, the latter being on the higher end of unaspirated stop ranges (Cho and Ladefoged, 1999). VOT is significantly longer before stressed word-medial syllables, but shorter before stressed word-initial syllables. For word-medial stressed syllables, VOT is also significantly longer when the syllable is in prosodic-word initial position. VOT length may have separate functions in Hawaiian unaspirated stops: strengthen a lexical word boundary especially before an unstressed syllable via shortening, but lengthen word-medially to demarcate a prosodic word boundary.

Prosodic modulations on the formant excursions of diphthongs

The excursions of the first two formants of diphthongs in Chinese, English, and Japanese were investigated to see how diphthongs are affected by the hierarchical prosodic structure. The production of /ai, au, ou/ was examined in Chinese and English, and /ai, au, ae/ in Japanese. Three prosodic contexts were examined: word-final, list-final, and IP (intonational phrase)-final positions. The results of GAM analysis of F1 and F2 show that (1) F2 was more affected than F1; (2) diphthong offset was more affected than the onset; (3) only the diphthong onset in Japanese was affected by the prosody. The by-language analysis further shows that the offset of diphthongs at word-final positions in Chinese was less resistant to the coarticulatory effect: F2 raises earlier and higher toward the end of the diphthong due to the influence of the following coronal consonant. Meanwhile, in English and Japanese /ai, ae/ with lower F2 and higher F1 and /au, ou/ with higher F1 and F2 at word-final positions were found, indicating hypoarticulation at lower prosodic boundaries. Some of the diphthong onsets in Japanese were influenced as well. The result suggests hyperarticulation as a prosodic strengthening effect in English and Japanese.

Boundary-induced prosodic strengthening and its function in interactive and read speech

This study investigates the functions of boundary-induced prosodic strengthening relative to speech style, focusing on English plosives and nasals in Intonational-Phrase(IP)-initial and IP-medial positions in interactive and read speech. Two accounts seek to explain the function of prosodic strengthening: syntagmatic contrast enhancement (SCE: enhancement of the contrast between neighboring consonants and vowels) (e.g., Cho & Keating, 2001) and paradigmatic contrast enhancement (PCE: enhancement of phonological contrasts) (e.g., Georgeton & Fougeron, 2014). For interactive speech, pairs of participants produced words while exchanging information about scenes; for read speech, each participant individually produced words in written sentences. For plosives, Voice-Onset-Time measurements showed SCE in read speech, with plosives being more consonant-like (less voiced) IP-initially than IP-medially, but PCE in interactive speech, with voiced and voiceless plosives being more distinct from each other and from other places of articulation IP-initially than IP-medially; spectral measures showed PCE in both interactive and read speech. These results suggest that speakers make plosives phonologically more distinct from one another in interactive speech to help listeners identify them better. Nasals were more consonant-like (less nasality) IP-initially than IP-medially in both interactive and read speech, showing SCE, attributable to nasals being phonetically and phonologically distinct from non-nasal consonants.

Prosodic strengthening in reference to the lexical pitch accent system in South Kyungsang Korean

AbstractTheories of the phonetics-prosody interface suggest that prosodic strengthening that arises with prosodic structuring is not simply a low-level phonetic phenomenon, but it serves as a phonetic hallmark of a higher-order prosodic structure in reference to linguistic (phonological) contrast. The present study builds on this theoretical premise by examining acoustic realization of the phonological tonal contrast in the lexical pitch accent system of South Kyungsang (SK) Korean. Results showed that phonetic realization of F0 and the degree of glottalization (as reflected in spectral tilt measures such as H1-A1c and H1-A3c) of vowels in vowel-initial words were systematically modulated by the higher-order prosodic structure, and that the prosodic-structural modulation gave rise to distinct prosodic strengthening effects as a function of the source of prosodic strengthening. In particular, the prominence-induced strengthening (due to focus) entailed a phonetic polarizing effect on the F0 contrast in a way that enhances the phonological High vs. Low tone contrast. The boundary-induced strengthening effect, on the other hand, could be better understood as enhancing the phonetic clarity of prosodic junctures. The distinct prosodic strengthening effects were further evident in the way that glottalization was fine-tuned according to prosodic structure and phonological (tonal) contrast. Prosodic strengthening effects were also found to interact with intrinsic vowel height, implying that the low-level phonetic effect may be under speaker control in reference to higher-order prosodic and phonological contrast systems of the language. Finally, the results informed a theoretical debate regarding whether the Low tone that contrasts with the High tone in word-initial position should be considered lexically specified vs. post-lexical assigned.

Prosodic-structural modulation of stop voicing contrast along the VOT continuum in trochaic and iambic words in American English

This study explores the phonetic nature of phonological stop voicing contrast in American English by investigating how phonetic implementation of the voicing contrast is modulated by the prosodic structure along the continuum of phonetic voicing. In particular, the present study examines (1) the effects of two kinds of prosodic strengthening that can arise with prosodic structuring, a boundary-related domain-initial strengthening (DIS) and a prominence-induced strengthening, and (2) the possible enhancement types of linguistic contrasts that can underlie prosodic strengthening. The phonetic voicing was estimated using the Integrated Voicing Index (IVI), taking into account both the voicing lag (positive VOT) and the voiced interval during the closure. Results obtained with initial stops in both trochaic and iambic words are encapsulated as follows. Under the influence of DIS, both voiced and voiceless stops were produced with an increase in voicelessness, showing an enhancement of structurally motivated syntagmatic (CV) contrast. The effect size was larger for voiced stops, yielding a boundary-induced phonetic reduction of voicing contrast. Under the influence of prominence (focus), both voiced and voiceless stops showed an increase in voicelessness only in trochaic words, but this time, it was voiceless stops that showed a far greater effect, resulting in a maximization of voicing contrast—i.e., an enhancement of paradigmatic contrast. Moreover, the reduced voicing for voiced stops under prominence even in the medial position indicates that voiced stops are realized in reference to the phonetic feature {vl. unaspirated} rather than {voiced}. These findings imply that seemingly non-contrastive low-level variation is indeed systematically modulated by the prosodic structure in reference to phonetic representations that regulate the phonetic implementation of phonological contrast in a given language. An alternative account is also discussed in the framework of Articulatory Phonology.

Prosodically-conditioned fine-tuning of coarticulatory vowel nasalization in English

This study explores the relationship between prosodic strengthening and linguistic contrasts in English by examining temporal realization of nasals (N-duration) in CVN# and #NVC, and their coarticulatory influence on vowels (V-nasalization). Results show that different sources of prosodic strengthening bring about different types of linguistic contrasts. Prominence enhances the consonant׳s [nasality] as reflected in an elongation of N-duration, but it enhances the vowel׳s [orality] (rather than [nasality]) showing coarticulatory resistance to the nasal influence even when the nasal is phonologically focused (e.g., mob-bob; bomb-bob). Boundary strength induces different types of enhancement patterns as a function of prosodic position (initial vs. final). In the domain-initial position, boundary strength reduces the consonant׳s [nasality] as evident in a shortening of N-duration and a reduction of V-nasalization, thus enhancing CV contrast. The opposite is true with the domain-final nasal in which N-duration is lengthened accompanied by greater V-nasalization, showing coarticulatory vulnerability. The systematic coarticulatory variation as a function of prosodic factors indicates that V-nasalization as a coarticulatory process is indeed under speaker control, fine-tuned in a linguistically significant way. In dynamical terms, these results may be seen as coming from differential intergestural coupling relationships that may underlie the difference in V-nasalization in CVN# vs. #NVC. It is proposed that the timing initially determined by such coupling relationships must be fine-tuned by prosodic strengthening in a way that reflects the relationship between dynamical underpinnings of speech timing and linguistic contrasts.

Prosodic Boundary Strengthening in the Phonetics–Prosody Interface

AbstractProsodic structure has been assumed to serve as a frame for articulation, so that phonetic shaping of abstract phonological representations is fine‐tuned as a function of the prosodic system of the language. The intricate relationship between phonetics and prosodic structure has been explored in the literature under the rubric of the phonetics–prosody interface. This paper reviews various aspects of the phonetics–prosody interface and discusses how prosodic structure modulates phonetic realization within and across languages. A particular attention is paid to boundary‐related prosodic strengthening (i.e., spatial and/or temporal expansion of articulation that arises in the vicinity of prosodic junctures), especially in association with domain‐initial positions (also known as domain‐initial strengthening, DIS, effects). Prosodic boundary strengthening is further discussed in terms of how it is language‐specifically fine‐tuned, how it is understood in dynamical terms, and how it relates to linguistic functions (as syntagmatic vs. paradigmatic contrast enhancement) that are all further conditioned by other factors of the linguistic sound system of individual languages such as the prominence system and the phonetic feature system.

Lexical stress and stop bursts in Pitjantjatjara: Feature enhancement of neutralized apicals and the coronal/velar contrast

This study investigates duration and spectral properties of the stop burst for /p t ʈc k/, the five oral stops of Pitjantjatjara, a language of Central Australia. We focus on stressed vs. unstressed syllables, with stressed syllables also being word-initial in Pitjantjatjara. Notably, the contrast between the apico-alveolar /t/ and the medial apico-postalveolar (retroflex) /ʈ/ is neutralized in initial position, which is the stressed position. We label this neutralized apical /T/, and show that the stop burst for this prosodically prominent apical has an even higher spectral center of gravity than either of its non-neutralized counterparts. By contrast, the velar /k/ shows a lower spectral center of gravity in stressed position. We suggest that this reflects an enhancement of the feature [grave], with the apical being “lighter” and the velar being “darker” under stress (the bilabial and the palatal show relatively few spectral effects, due to acoustic and coarticulatory considerations respectively). However, the stressed apical /T/ does not have a longer stop burst duration in initial position, a result that is contrary to the other stop bursts examined here, and which goes against expected patterns of prosodic strengthening. We suggest that this is because a phonetic feature, short [burst duration], is an important cue to apical consonant identity in a system with many places of articulation.

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

This 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.

Voice quality strengthening and glottalization

Prominence and phrase-initial position strongly favor the presence of word-initial glottalization in English and other languages. This suggests that word-initial glottalization may arise from prosodic strengthening – the phenomenon by which sounds are more ‘strongly’ articulated in stronger prosodic positions. However, if word-initial glottalization is due to prosodic strengthening, what exactly is being strengthened? The goal of this study is to determine whether voice quality is strengthened in vowels and sonorants, and whether this type of strengthening is consistent with word-initial glottalization. Prominent and/or phrase-initial voicing in English and Spanish was analyzed articulatorily using electroglottography. The results reveal that voicing during word-initial vowels in English and Spanish has increased contact under prominence, but not at phrasal onsets. Non-prominent initial vowels and sonorants are characterized by a decrease in contact, which I argue is inconsistent with both word-initial glottalization and voice quality strengthening. Based on the results, a prominence-driven account of word-initial glottalization is proposed and motivated.

Effects of prosodic strengthening and lexical boundary on /s/-stop sequences in English

This study examined how the effects of prosodic strengthening (from prosodic boundary and accent) and lexical boundary (e.g., “ice # can” vs. “eye # scan”) are acoustic-phonetically realized on English /s/-stop sequences in a sentence. First, the domain-initial strengthening effect was not strictly confined to the first segment, but could extend into the second consonant and, at least partially, into the following vowel in the #/sCV/ sequence (e.g., in “scan”). Second, the accent-induced strengthening effect was robust in all acoustic measures for the #/sCV/ sequence. Third, prosodic strengthening arising with boundary and accent gave rise to the “shortened” VOT for the voiceless stop in the #/sCV/ sequence, suggesting that prosodic strengthening can operate on the phonetic manifestation of a phonological rule to reinforce the language-specific phonetic feature, which is, in this case, {-spread glottis}. Fourth, domain-initial strengthening and accent-induced strengthening differ substantially in some aspects, suggesting that they may be encoded separately in speech production process. Finally, “ice # can” and “eye # scan” were indeed very differently realized, suggesting that the underlying lexical boundary is signaled by fine-phonetic details even when the sequences occurred phrase-internally where they appeared to be homophonous, at least impressionistically, and syllabified the same.

Prosodic strengthening in the articulation of English /æ/

Prosodic strengthening in the articulation of English /æ/

Phonetic richness can outweigh prosodically-driven phonological knowledge when learning words in an artificial language

How do Dutch and Korean listeners use acoustic–phonetic information when learning words in an artificial language? Dutch has a voiceless ‘unaspirated’ stop, produced with shortened Voice Onset Time (VOT) in prosodic strengthening environments (e.g., in domain-initial position and under prominence), enhancing the feature {−spread glottis}; Korean has a voiceless ‘aspirated’ stop produced with lengthened VOT in similar environments, enhancing the feature {+spread glottis}. Given this cross-linguistic difference, two competing hypotheses were tested. The phonological-superiority hypothesis predicts that Dutch and Korean listeners should utilize shortened and lengthened VOTs, respectively, as cues in artificial-language segmentation. The phonetic-superiority hypothesis predicts that both groups should take advantage of the phonetic richness of longer VOTs (i.e., their enhanced auditory–perceptual robustness). Dutch and Korean listeners learned the words of an artificial language better when word-initial stops had longer VOTs than when they had shorter VOTs. It appears that language-specific phonological knowledge can be overridden by phonetic richness in processing an unfamiliar language. Listeners nonetheless performed better when the stimuli were based on the speech of their native languages, suggesting that the use of richer phonetic information was modulated by listeners' familiarity with the stimuli.

Prosodic conditioning of phonetic detail in German plosives

This study investigates the prosodic conditioning of phonetic details which are candidate cues to phonological contrasts. German /b, d, g, p, t, k/ were examined in three prosodic positions. Lenis plosives /b, d, g/ were produced with less glottal vibration at larger prosodic boundaries, whereas their VOT showed no effect of prosody. VOT of fortis plosives /p, t, k/ decreased at larger boundaries, as did their burst intensity maximum. Vowels (when measured from consonantal release) following fortis plosives and lenis velars were shorter after larger boundaries. Closure duration, which did not contribute to the fortis/lenis contrast, was heavily affected by prosody. These results support neither of the hitherto proposed accounts of prosodic strengthening (Uniform Strengthening and Feature Enhancement). We propose a different account, stating that the phonological identity of speech sounds remains stable not only within, but also across prosodic positions (contrast-over-prosody hypothesis). Domain-initial strengthening hardly diminishes the contrast between prosodically weak fortis and strong lenis plosives.

Prosodic Strengthening in Transboundary V-to-V Lingual Movement in American English

This study investigates how prosodic strengthening is kinematically manifested in V-to-V lingual movement in English CV#CV context (where # is a prosodic boundary). Results showed that both boundary and accent gave rise to a kind of prosodic strengthening (showing spatial and temporal expansion), but exact kinematic patterns of prosodic strengthening were different as a function of the type of gesture (tongue lowering versus raising) associated with different vowels (/i/to-/É‘/ vs. /É‘/-to-/i/) and the source of prosodic strengthening (boundary versus accentuation). This implies that speakers must know about prosodic structure and differentiate the two sources of prosodic strengthening in a systematic finegrained fashion. From a theoretical point of view regarding a mass-spring gestural model, results suggested that kinematic patterns of prosodic strengthening could not be fully accounted for by any particular dynamical parameter, presenting a complex nature of prosodic strengthening. The results also implied that the theory of the π-gesture (the prosodic boundary gesture) under the rubric of the massspring gestural model needs to be refined in terms of how the theory defines the exact scope of the π-gesture’s influence in the temporal dimension and how it differentiates boundary-induced articulation from an accent-induced one.

Prosodic strengthening of German fricatives in duration and assimilatory devoicing

This study addressed prosodic effects on the duration of and amount of glottal vibration in German word-initial fricatives /f, v, z/ in assimilatory and non-assimilatory devoicing contexts. Fricatives following /ə/ (non-assimilation context) were longer and were produced with less glottal vibration after higher prosodic boundaries, reflecting domain-initial prosodic strengthening. After /t/ (assimilation context), lenis fricatives (/v, z/) were produced with less glottal vibration than after /ə/, due to assimilatory devoicing. This devoicing was especially strong across lower prosodic boundaries, showing the influence of prosodic structure on sandhi processes. Reduction in glottal vibration made lenis fricatives more fortis-like (/f, s/). Importantly, fricative duration, another major cue to the fortis-lenis distinction, was affected by initial lengthening, but not by assimilation. Hence, at smaller boundaries, fricatives were more devoiced (more fortis-like), but also shorter (more lenis-like). As a consequence, the fortis and lenis fricatives remained acoustically distinct in all prosodic and segmental contexts. Overall, /z/ was devoiced to a greater extent than /v/. Since /z/ does not have a fortis counterpart in word-initial position, these findings suggest that phonotactic restrictions constrain phonetic processes. The present study illuminates a complex interaction of prosody, sandhi processes, and phonotactics, yielding systematic phonetic cues to prosodic structure and phonological distinctions.

Prosodic effects on acoustic cues to stop voicing and place of articulation: Evidence from Radio News speech

This study examines the effects of prosody on the acoustic cues of stop consonants, based on speech from the Boston University Radio News corpus. An investigation of VOT, f 0, closure duration, burst amplitude and spectral characteristics provide evidence for a primary effect of accent (a level of phrasal prominence) on these measures as cues to stop voicing and/or place of articulation. There are robust, significant effects of accent on the acoustic cues for both voicing and place of articulation, exhibiting a general pattern of prosodic strengthening. However, the accent effect on voicing cues results in the enhancement of the phonological voice contrast, whereas the effect on acoustic cues to place of articulation does not similarly enhance the place contrast. Comparison of η 2 values shows that accent effects are strongest on those measures that are weak cues to the phonological contrast, and weakest on the measures that are strong cues. While there are no observed strengthening effects of phrasal position on voicing cues for /t/ and /d/, acoustic variability is reduced in phrase-initial position.