Stop Closure Duration Research Articles

Acoustic properties of bilabial trills in Medumba

Olson (2022) claims that all bilabial trills in phonemic systems are releases of stops. They are either part of complex phonemes that involve stop-trill sequences, e.g. /pᴮ, bᴮ, ᵐbᴮ, tᴾ/, or they pattern as allophones of a compressed or fricative vowel following a stop, e.g. [pʙ̩, bʙ̩, tʙ̩]. Olson notes that the stop-trill phonemes behave as obstruents. I provide acoustic evidence for this claim. Previous studies indicate that the closure of /b/ is shorter than that of /p, ᵐb/ and that the oral portion of the closure of /ᵐb/ is very short (~30–40 ms). Likewise, it has been shown that the stop closure of /bᴮ/ is shorter than that of /pᴮ, ᵐbᴮ/ and that the oral portion of the stop closure of /ᵐbᴮ/ is very short (e.g. Olson 2023). For Medumba (Cameroon), we find similar patterning. The mean stop closure durations of /bᴮ, ᵐbᴮ/ are 137 ms (s.d. = 28, n = 58) and 192 ms (s.d. = 47, n = 28), respectively. The difference is very highly significant: t(37) = 5.79, p < 0.001 (one-tailed). The mean oral stop closure duration of /ᵐbᴮ/ is 26.6 ms (s.d. = 6.2, n = 28). The finding that stops with bilabial trill releases behave as obstruents is important, because elsewhere they have been categorized with /r/ assuming that they are sonorants.

Talker adjustment to perceived communication errors

During conversation, talkers may adapt their speech in a variety of ways. One form of adaptation is clear speech, in which a talker hyperarticulates when faced with specific communication challenges. In this study, we investigated how phonetic adaptation is affected by the nature of apparent miscommunication. To do so, we utilized a common feature of American English dialects, in which intervocalic /t/ is realized as a voiced flap rather than an unvoiced, fully articulated stop before unstressed syllables, causing words like petal and pedal to sound similar. Flapped /t/ may become more distinct compared to /d/ during clear speech. Using a faux-computer training paradigm, we provided artificial feedback on subjects’ speech. When subjects said a word (e.g., petal) the computer would either interpret the word correctly (i.e., it guesses petal) or incorrectly (it guesses pedal, kettle or ???). We measured talkers’ produced word length, initial-syllable vowel length, and medial consonant stop closure or flap consonant duration in both their first and second utterances of each trial. We found that participants produced longer words, vowels, and stop closure durations in response to feedback that contained an error compared to correct feedback. Participants also changed their flapped productions to stops most often and lengthened their stop closures to a greater degree following voicing errors compared to the other error conditions. Our findings indicate that interlocutors’ productions may change along different acoustic dimensions depending on the kind of miscommunication they experience. Broadly, our findings indicate a need to consider how phonetic adaptation in the form of clear speech is affected by the nature of miscommunication during conversational interaction.

Effects of vowel duration on the perceived naturalness of English monosyllabic words ending in a stop: Some preliminary findings*

Preliminary findings are reported from five experiments testing the perceived naturalness of word tokens whose vowel durations are altered. The stimuli were minimal pairs of English words ending in a voiced/voiceless plosive. Results show an asymmetric effect of shortening and lengthening of the vowel on the perceived naturalness of the word. Incremental shortening of vowel duration initially shows a stable degree of perceived naturalness but rapidly deteriorates beyond a certain point. On the contrary, only a small degree of lengthening of the vowel made the perceived naturalness of the word quickly decay, but there was a floor effect such that the perceived degree of naturalness does not lower beyond a certain level. Further, the tokens with the original vowel duration were not always scored higher than the stimuli with a small degree of shortening. Future studies should address the issue of speaking rate and the ratio between the vowel and the stop closure duration to better understand the phenomenon. The issue investigated here has implications on the role of prototypical exemplars in the perception of phonotactic naturalness.

Why phonetically-motivated constraints do not lead to phonetic determinism: The relevance of aspiration in cueing NC sequences in Tumbuka

This paper examines the role of phonetic cues to postnasal laryngeal contrasts, language-specific differences in the use of these cues, and the phonetic naturalness of the different cues. While many studies have shown that long stop closure duration is a well-established cue to voicelessness in the postnasal context (see, e.g., Cohn & Riehl 2012, who claim this to be a universal property), the present study focusses on the role of aspiration noise in maintaining a voicing contrast in the postnasal environment. It provides experimental data from the Bantu language Tumbuka to illustrate that aspiration noise can preserve a postnasal laryngeal contrast even when stop closure duration is short. Though typologically less common, we show that the use of aspiration as a cue is also phonetically motivated. Furthermore, we show that such phonetic motivation should not be directly incorporated into phonology (e.g., as markedness constraints in OT). Instead, we employ the BiPhon model (Boersma 2007), which allows for a strict distinction between the modules of phonetics and phonology, and which formalizes the mapping of phonetic cues onto phonological representations via cue constraints, avoiding the problem of phonetic determinism.

An exploratory study of voicing-related differences in vowel duration as compensatory temporal adjustment in Italian and Polish

Over a century of phonetic research has established the cross-linguistic existence of the so called “voicing effect”, by which vowels tend to be shorter when followed by voiceless stops and longer when the following stop is voiced. However, no agreement is found among scholars regarding the source of this effect, and several causal accounts have been advanced. A notable one is the compensatory temporal adjustment account, according to which the duration of the vowel is inversely correlated with the stop closure duration (voiceless stops having longer closure durations than voiced stops). The compensatory account has been criticised due to lack of empirical support and its vagueness regarding the temporal interval within which compensation is implemented. The results from an exploratory study of Italian and Polish suggest that the duration of the interval between two consecutive stop releases in CVCV words in these languages is not affected by the voicing of the second stop. The durational difference of the first vowel and the stop closure would then follow from differences in timing of the VC boundary within this interval. While other aspects, like production mechanisms related to laryngeal features effects and perceptual biases cannot be ruled out, the data discussed here are compatible with a production account based on compensatory mechanisms.

Language Specificity in Phonetic Cue Weighting: Monolingual and Bilingual Perception of the Stop Voicing Contrast in English and Spanish

Background/Aims: This work examines the perception of the stop voicing contrast in Spanish and English along four acoustic dimensions, comparing monolingual and bilingual listeners. Our primary goals are to test the extent to which cue-weighting strategies are language-specific in monolinguals, and whether this language specificity extends to bilingual listeners. Methods: Participants categorized sounds varying in voice onset time (VOT, the primary cue to the contrast) and three secondary cues: fundamental frequency at vowel onset, first formant (F1) onset frequency, and stop closure duration. Listeners heard acoustically identical target stimuli, within language-specific carrier phrases, in English and Spanish modes. Results: While all listener groups used all cues, monolingual English listeners relied more on F1, and less on closure duration, than monolingual Spanish listeners, indicating language specificity in cue use. Early bilingual listeners used the three secondary cues similarly in English and Spanish, despite showing language-specific VOT boundaries. Conclusion: While our findings reinforce previous work demonstrating language-specific phonetic representations in bilinguals in terms of VOT boundary, they suggest that this specificity may not extend straightforwardly to cue-weighting strategies.

L1 Interference in Koreans' Perception of Released Word-final Stops in English

This study investigated L1 interference in the perception of released word-final stops in English by performing perception experiments on Korean and English listeners. Stimuli with conflicting cues were used in experiments in which the ‘long CV’ and the ‘short vowel CV’ were rejoined with six silent closure duration intervals and two release bursts of [g] and two release bursts of [k]. The perception results show that Korean listeners perceived significantly more [k] compared to English listeners when ‘k’ release was attached to a ‘long CV.’ We suggest that this is due to different phonological systems in Korean and English. In Korean, a released stop occurs only in the onset position in which the VOT and the stop closure duration are important acoustic cues for the identity of a stop. Thus, the English coda [k] with voiceless release burst could be perceived as an onset with long VOT, namely [k], by Korean listeners. In contrast, English listeners mostly perceived a voiced stop due to the long preceding vowel (cf. Raphael, 1972). With the stimuli of ‘short CV’ with ‘g’ release, Korean listeners perceived significantly more [g] than NE listeners did. English coda [g] with a voiced release may be perceived as an onset [g] with a short VOT by Korean listeners. In contrast, English listeners perceived a voiceless stop [k] due to the preceding short vowel. This paper also showed that Korean listeners would perceive finer distinctions than two levels of release, ‘g’ release and ‘k’ release.

Evidence for active cavity expansion through advanced lingual place of constriction in voiced geminates

Geminate voicing requires both active and passive cavity expansion in order to delay the equalization of subglottal and supraglottal pressure (Ohala 1983, Ham 2001). Studies report differences in stop closure duration (Lahiri & Hankamer 1988) and pre-geminate vowel duration as cues to the laryngeal contrast. Following Schroeder (1967), Mermelstein (1967), and Iskarous (2010), we present results from formant transitions in the VC:V context and the anti-symmetric Fourier component coefficient, an = -2 (Fn-fn)/fn, to partially recover the area function of the vocal tract behind the geminate constriction. Voiced geminates exhibit significantly higher and positive coefficient values than their voiceless counterparts which implies that measured Fn values for voiced geminates are lower than their neutral tract formant values. This finding indicates that voiced geminates have a more anterior constriction compared to their voiceless counterparts. Without ruling out the role of passive cavity expansion through the cheek muscles, we conclude that in order to delay the pressure equalization the lingual constriction in voiced geminates is maintained at an anterior location compared to voiceless geminates in Bangla. Results from the slopes of first order F2 locus-equations are also presented to measure the differences in coarticulatory resistance between the voiced and voiceless geminates.Geminate voicing requires both active and passive cavity expansion in order to delay the equalization of subglottal and supraglottal pressure (Ohala 1983, Ham 2001). Studies report differences in stop closure duration (Lahiri & Hankamer 1988) and pre-geminate vowel duration as cues to the laryngeal contrast. Following Schroeder (1967), Mermelstein (1967), and Iskarous (2010), we present results from formant transitions in the VC:V context and the anti-symmetric Fourier component coefficient, an = -2 (Fn-fn)/fn, to partially recover the area function of the vocal tract behind the geminate constriction. Voiced geminates exhibit significantly higher and positive coefficient values than their voiceless counterparts which implies that measured Fn values for voiced geminates are lower than their neutral tract formant values. This finding indicates that voiced geminates have a more anterior constriction compared to their voiceless counterparts. Without ruling out the role of passive cavity expansion through the ...

Acoustics of the tense-lax stop contrast in Semarang Javanese

Javanese has a contrast between tense and lax stops. While both tense and lax stops are voiceless and unaspirated, the contrast at least in word-initial position is realized through acoustic differences in the following vowel, including lower f0, breathier voice quality, and higher F1 for the lax stops relative to their tense counterparts. However, previous reports have indicated substantial cross-speaker variation, and in some cases involve differing characterizations of the acoustic contrast, possibly due to small sample sizes. Moreover, it is still unclear whether (and how) this contrast is maintained in word-final position. In this study, we investigate the tense-lax contrast based on audio recordings of 27 speakers of Central Javanese from Semarang, Indonesia who each read 30 or more items with a word-initial or word-final stop in a carrier phrase. Stops and their adjacent vowels were hand-annotated, and measurements were taken including voice onset and offset time, stop closure and release duration, f0, formant frequencies, and spectral tilt and noise levels. Discussion will focus on how the tense-lax contrast is realized in both word-initial and word-final positions, as well as how different acoustic correlates co-vary within and across speakers.

An acoustic study of pulmonic and ejective stops in the final coda position in Yucatec

In this study, I present an acoustic analysis of contrast between pulmonic and ejective stops in the phrase final coda position in Yucatec, a Mayan language. Ejective consonants are found in about 16% of the world’s language, and there are a relatively large number of acoustic studies about these sounds. However, a significant empirical shortcoming of the previous studies is their exclusive focus on the acoustic realization of ejective consonants in the syllable onset position. This is partly due to a cross-linguistic tendency that ejective consonants are prohibited to occur in the syllable coda position. Therefore, data from Yucatec, which allows ejective consents to occur in the syllable coda position, fill the empirical gap. This study compared pulmonic stop /k/ and ejective stop /k’/ in the phrase final coda position taking a number of acoustic measurements. The results showed (1) stop release is shorter for the ejective, (2) stop closure duration is shorter for the ejective, (3) stop release noise intensity is higher for the ejective, and (4) the contrast between pulmonic and ejective stops affects the voice quality of the preceding short vowel (H1-H2 is lower for the short vowel preceding the ejective).

Discriminant variables for plosive- and fricative-type single and geminate stops in Japanese

Previous studies suggested that a plosive-type geminate stop in Japanese is discriminated from a single stop with variables of stop closure duration and subword duration that spans from the mora preceding the geminate stop to the vowel following the stop. However, this suggestion does not apply to a fricative-type geminate stop that does not have a stop closure. To overcome this problem, this study proposes Inter-Vowel Interval (IVI) and Successive Vowel Interval (SVI) as discriminant variables. IVI is the duration between the end of the vowel preceding the stop and the beginning of the vowel following the stop. SVI is the duration between the beginning of the vowel preceding the stop and the end of the vowel following the stop. When discriminant analysis was conducted between single and geminate stops of plosive and fricative types using IVI and SVI as independent variables, the discriminant ratio was very high (99.5%, n = 368). This result indicates that IVI and SVI are the general variables that represent acoustic features distinguishing Japanese single and geminate stops of both plosive and fricative types. [This study was supported by JSPS KAKENHI Grant Numbers 24652087, 25284080, 26370464 and by Aichi-Shukutoku University Cooperative Research Grant 2013-2014.]

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.

Acoustic cue weighting in perception and production of English and Spanish

We present data quantifying the use of multiple acoustic dimensions in the perception and production of word-initial stops in Spanish and English in bilinguals and monolinguals, with a focus on the stability of individuals’ cue weighting strategies across languages and modalities. Early Spanish-English bilinguals who use both languages on a regular basis, along with control groups of monolingual Spanish and English speakers, categorized stop-initial CV syllables covarying in Voice Onset Time (VOT), fundamental frequency at vowel onset (f0), first formant onset frequency (F1), and stop closure duration. Individual perceptual cue weights were calculated via logistic regression, and these weights were compared with the same speakers’ use of the corresponding acoustic dimensions in their productions of the stop contrast. Preliminary results suggest that bilingual listeners’ perceptual cue weighting strategies correspond across Spanish and English; that is, individuals who weight a given cue more heavily than average in English also weight that cue heavily in Spanish. However, in line with previous work, correspondences between a given individual's use of the acoustic dimensions across perception and production are more elusive.

Electropalatography in the description and treatment of speech disorders in five children with cerebral palsy

Some children with cerebral palsy have articulation disorders that are resistant to conventional speech therapy. The aim of this study was to investigate whether the visual feedback method of electropalatography (EPG) could be an effective tool for treating five children (mean age of 9.4 years) with dysarthria and cerebral palsy and to explore whether training improved the posteriorly placed articulation of the Swedish dental/alveolar target consonants /t/, /d/, /n/ and /s/ produced in different positions. An EPG analysis was conducted and some of the data were combined with a perceptual analysis. A more anterior placement was seen after treatment for the target sounds. Features of diagnostic importance revealed were unusual tongue–palate contacts, such as double articulation and abnormally retracted articulation. A possible change in stop closure duration was indicated. The results suggest that EPG could be of potential benefit for diagnosing, treating and describing articulation errors associated with cerebral palsy.

Individual differences in the production and perception of the voicing contrast by native and non-native speakers of English

Investigations of acoustic characteristics of speech production and their perceptual correlates often determine that various common patterns are observed among groups of talkers/listeners. It is also sometimes reported that a certain amount of noise occurred in the data, i.e., that not all subjects fit general patterns that were observed. While individuals who do not demonstrate typical patterns are often viewed as outliers, subjects who represent exceptions also provide important information. The present study reports findings obtained from 15 native speakers of English and 15 non-native (native Mandarin) speakers of English who were recorded producing several final-position voiced/voiceless CVC word pairs and who also made voicing judgments about voiced/voiceless cognates produced by other native English and native Mandarin speakers. All native subjects in the present study produced multiple acoustic cues in making voicing distinctions (e.g., vowel duration, final stop closure duration, voicing during final stop occlusion, release burst); however, not all subjects used all these acoustic cues or the same combinations of cues in their voicing contrasts. Only about half the native Mandarin speakers used multiple acoustic cues in attempting to produce a voicing contrast. Various group trends, as well as subgroup variations, in production and perception will be discussed.

The behavior of affricates under restricted lengthening conditions

This study uses affricates as a test case for lengthening processes in speech. In general, consonants can lengthen as the result of phonological factors, such as a geminating suffix, or as the result of phonetic factors such as position within a phrase (Keating et al. 2003, Byrd et al. 2000, 2005). In Hungarian and many other languages, however, the presence of an additional consonant restricts phonological lengthening because CCC clusters containing geminates are ill‐formed (Kenesei et al. 1998). Acoustic duration measurements were used to examine whether this restriction also holds for phonetic lengthening. Initial results from three male Hungarian speakers indicate that it does not. Consonants in phrase‐final position are significantly longer than their counterparts in phrase‐medial position, whether they stand alone or in a cluster. A focus on lengthened affricates, however, reveals that the ‘‘shape’’ of lengthening differs in these two conditions. Affricates in the stand‐alone condition lengthen in a lopsided fashion, showing increases primarily in frication duration; those in the cluster condition lengthen more symmetrically, with increases in both stop closure and frication durations. These findings provide new support for the idea that affricates possess different structures at different levels of analysis (Lombardi 1990, Clements 1999).

An acoustic and perceptual investigation of the geminate and singleton stop contrast in Japanese

Segmental durations are known to be heavily influenced by changes in speech rate such that the durations of members of two contrasting length categories may overlap [Pickett et al. ‘‘Effects of speaking rate on singleton/geminate contrast in Italian,’’ Phonetica 56, 135–157 (1999); Hirata & Whiton, ‘‘Relational acoustic invariance in the single/geminate stop distinction in Japanese,’’ J. Acoust. Soc. Am. 117, 2569 (2005)]. Given this, questions arise as to how category distinction is achieved for contrasts signaled by differences in segmental duration. This study investigates the question by examining the production and perception of the Japanese singleton versus geminate stop contrast by adult native speakers. Six native Japanese speakers produced disyllabic words with medial singleton and geminate stops at three speaking rates. Duration of stop closure and a number of relational timings between the closure duration and other segments were examined as potential rate-independent measures distinguishing the two categories. The ratios of stop closure to the preceding mora as well as stop closure to the following vowel remained stable across speaking rate and accurately classified naturally produced tokens. Ten native Japanese listeners participated in an identification task to examine the perceptual relevance of these relational timings. The results indicated an influential role of preceding mora duration and a small role of following vowel duration. The results also suggested that nondurational factor(s) influence perception of the stop length contrast.

Relational acoustic invariance in the single/geminate stop distinction in Japanese

This study addressed an issue in the theory of relational acoustic invariance [Pickett et al., Phonetica 56, 135–157 (1999)]. The question was whether an invariant acoustic property exists for distinguishing Japanese single and geminate voiceless stops across different speaking rates. Four native Japanese speakers produced disyllabic words with single and geminate voiceless stops spoken in a carrier sentence at three speaking rates. Durations of sentences, words, stop closures, and vowels preceding the contrasting stops were measured. Ratios of geminate to single stop closures, geminate words to single words, closures to preceding vowels, and closures to words were calculated. The stop closure duration significantly overlapped between the single and geminate categories across rates. However, the ratio of geminate to single closure duration was unaffected by rate. Among the measures examined, the ratio of closure to word duration (0.35 as an optimal boundary) best classified all single and geminate tokens with 95.7–98% accuracy. These results suggest that, in spite of overlap in absolute closure duration between single and geminate stops, there is a relationally invariant measure that divides the two phonemic categories across rates and speakers, supporting the theory of relational acoustic invariance.

Underlying Voicing in Majorcan Catalan Word-Final Stop-Liquid Clusters

This study investigates the extent to which phonetic voicing is maintained inword-final clusters composed of an underlying voiced stop followed by nonsyllabic/l/ or /r/ in Majorcan Catalan. Electropalatographic and acoustic data forfive speakers of this Catalan dialect reveal that, in agreement with the non-syllabicstatus of the liquid, voicing for /l/ is only available if occurring during the precedingstop. The rhotic is always phonetically voiceless. Speakers differ regarding theextent to which they keep the underlying stop voicing distinction and the productionstrategies they use for that purpose. This distinction is highly robust and distributedover the entire syllable in nasal-stop-/l/ clusters for some speakers, butmuch less clear or absent for those speakers who devoice /l/ as a general rule.Underlying stop voicing is cued primarily by stop closure duration and vocal foldvibration, or else by closure duration rather than by voicing. It may be concludedthat the word-final devoicing process operating in Catalan does not apply toMajorcan Catalan tautosyllabic stop clusters with a liquid, and that phonetic voicingmay affect just the stop or both the stop and the liquid. The implications ofthese findings for sound change are discussed.

Supralaryngeal mechanisms of the voicing contrast in velars

This study investigates supralaryngeal mechanisms of the two way voicing contrast among German velar stops and the three way contrast among Korean velar stops, both in intervocalic position. Articulatory data won via electromagnetic articulography of three Korean speakers and acoustic recordings of three Korean and three German speakers are analysed. It was found that in both languages the voicing contrast is created by more than one mechanism. However, one can say that for Korean velar stops in intervocalic position stop closure duration is the most important parameter. For German it is closure voicing. The results support the phonological description proposed by Kohler (1984).