Voice Onset Time Research Articles

Underpinnings of explicit phonetic imitation: perception, production, and variability

This work tests the relative role of perception- and production-based predictors, and the relationship between them, in imitation of artificial accents varying in voice onset time (VOT), using a paradigm designed to target distinct sub-processes of imitation. We examined how explicit imitation of sentences differing systematically in voice onset time (VOT) was influenced by the type of VOT manipulation (lengthened vs. shortened) and by the presence vs. absence of voice-related variability in exposure. In contrast to previous work, participants imitated shortened as well as lengthened VOT, albeit with both qualitative and quantitative differences across the two manipulation types. The presence of voice-related variability inhibited imitation, but this inhibition was mitigated by a preceding session with no voice-related variability (i.e., sentences were acoustically identical except for VOT). We then tested the extent to which individual performance on the accent imitation task was related to performance on three other tasks: 1) discrimination of the target accents, 2) imitation of words in isolation drawn from a VOT continuum, and 3) discrimination of these same words. Performance on the accent discrimination task and the word-level imitation task, but not the word-level discrimination task, were independently predictive of accent imitation. Results are consistent with a conceptualization of explicit imitation as the sum of automatic phonetic convergence processes overlaid with distinct, controlled perceptual and articulatory factors that pattern differently across individuals. Phonetic imitation should not be considered as a monolithic skill, and models predicting variation in imitative ability must consider not only the potential sources of individual variability, but also at what level these sources of variability exert their influence. 

도호쿠 일본어의 폐쇄음 지각에 있어서 voice onset time(VOT)과 후속모음 fundamental frequency(F0)의 역할*

Tohoku Japanese is known to have voiced stops without pre-voicing in word-initial position, whereas traditional or conservative Japanese has voiced stops with pre-voicing in the same position. One problem with this devoicing of voiced stops is that it affects the distinction between voiced and voiceless stops because their voice onset time (VOT) values overlap. Previous studies have confirmed that Tohoku speakers use post-stop fundamental frequency (F0) as an acoustic cue along with VOT to avoid overlap. However, the role of post-stop F0 as a perceptual cue in this region has barely been investigated. Therefore, this study explored the role of post-stop F0 in stop voicing perception along with VOT. Several perception tests were conducted using resynthesized stimuli, which were manipulated along a VOT continuum orthogonal to an F0 continuum. The results showed no significant regional difference (Tohoku vs. Chubu) for nonsense words (/ta-da/). However, for meaningful words (/pari/ ‘Paris’ vs. /bari/ ‘Bali,’ /piza/ ‘pizza’ vs. /biza/ ‘visa’), a significant word effect was found, and it was confirmed that some listeners utilized the post-stop F0 more consistently and steadily than others. Based on these results, we discuss innovative listeners who may lead the change in the perception of stop voicing.

Kimchi or gimchi? Perceived similarity between Korean lenis and Japanese voiced/voiceless stop sounds

When distinguishing stop consonants, Korean listeners use the fundamental frequency of the following vowel (F0) as well as the voice onset time (VOT). However, it is unclear whether the F0 and VOT of natural speech sounds play an effective role in hearing nonnative stops. In the present study, we examined whether Korean listeners perceive Japanese voiced stops, rather than Japanese voiceless stops, as being similar to Korean lenis stops depending on F0 and VOT. Native Korean listeners matched a speech sound starting with either a Japanese voiced or voiceless stop to a target. The targets were meaningful visual words starting with a lenis stop in Experiment 1 and meaningless speech sounds starting with a lenis stop in Experiment 2. Native Japanese listeners, who primarily use VOT for stop distinction, also participated in Experiment 2. The results revealed that the extent to which Korean listeners chose voiced stops was influenced consistently by F0, and the pattern of results differed between Korean and Japanese listeners. These findings suggest that even when hearing natural speech sounds, Korean listeners use F0 when judging the similarity between lenis and nonnative stops.

Integration of fundamental frequency and voice-onset-time to voicing categorization: Listeners with normal hearing and bimodal hearing configurations.

This study investigates the integration of word-initial fundamental frequency (F0) and voice-onset-time (VOT) in stop voicing categorization for adult listeners with normal hearing (NH) and unilateral cochlear implant (CI) recipients utilizing a bimodal hearing configuration [CI + contralateral hearing aid (HA)]. Categorization was assessed for ten adults with NH and ten adult bimodal listeners, using synthesized consonant stimuli interpolating between /ba/ and /pa/ exemplars with five-step VOT and F0 conditions. All participants demonstrated the expected categorization pattern by reporting /ba/ for shorter VOTs and /pa/ for longer VOTs, with NH listeners showing more use of VOT as a voicing cue than CI listeners in general. When VOT becomes ambiguous between voiced and voiceless stops, NH users make more use of F0 as a cue to voicing than CI listeners, and CI listeners showed greater utilization of initial F0 during voicing identification in their bimodal (CI + HA) condition than in the CI-alone condition. The results demonstrate the adjunctive benefit of acoustic hearing from the non-implanted ear for listening conditions involving spectrotemporally complex stimuli. This finding may lead to the development of a clinically feasible perceptual weighting task that could inform clinicians about bimodal efficacy and the risk-benefit profile associated with bilateral CI recommendation.

Laryngeal contrasts in Hadza occlusives

Laryngeal contrasts in consonants are found in nearly all languages. Two-way laryngeal contrasts are common in western European languages, and three- and four-way systems are attested, for example, in many South Asian languages. The current study presents acoustic data on laryngeal contrasts in Hadza, a language isolate spoken by ∼1200 people (Brian Wood, pc.) in Tanzania. Hadza contains multiple complex consonant types, including clicks and ejectives, as well as aspiration and prenasalization. Some previous descriptions suggested a three-way contrast in stops (e.g., /t tʰ d/) and affricates (e.g., t⌢s t⌢sʰ d⌢z), and also a two-way contrast in clicks (e.g., /! !ʰ/) (Tucker et al., 1977; de Voogt, 1992), but did not offer corroborating phonetic evidence. Sands et al. (1996) documented the expected distinction in Voice Onset Time (VOT) between voiceless unaspirated and aspirated stops, but they did not find VOT differences for clicks or affricates. Using wordlist data collected in 2022, this study presents temporal measurements, including VOT, to examine the phonetic properties of laryngeal contrasts in Hadza occlusives and, especially, to evince an aspiration contrast in affricates and clicks previously unsubstantiated in the literature. These results resolve discrepancies between past research and further elucidate the laryngeal system of Hadza.

Acoustic analysis of voicing errors in children with childhood apraxia of speech

Childhood apraxia of speech (CAS) is a complex neurological speech sound disorder (SSD) that involves impaired speech motor planning and programming. Speech characteristics of CAS include difficulty sequencing speech movements in the absence of muscle weakness resulting in segmental and suprasegmental speech deficits. Past work indicates that children with CAS are delayed in acquisition of voicing contrasts, and are often perceived to produce errors or distortions of voicing. However, not all past studies employed acoustic analyses to assess voicing characteristics in CAS. This study will use voice onset time (VOT) to analyze the voicing contrast in children with CAS (aged 8;0 to 15;11) compared to peers with residual speech sound disorder (RSSD) and typical development (TD). VOT of initial consonants from twelve children (CAS = 4, RSSD = 4, TD = 4) will be assessed in words of varying length, stress pattern and target complexity. Given that children with CAS are known to experience greater articulatory breakdowns in phoneme sequences of increasing length and complexity, we expect that group differences will increase with task complexity. Overall, based on past work, we also predict that children with CAS will demonstrate shorter and/or more variable VOTs for plosives than children with SSD and TD.

Using automatic acoustic analysis to reveal disruptions to speech articulation in individuals at risk for psychosis

Individuals who are experiencing attenuated psychosis symptoms (placing them at clinical high risk for developing psychosis) exhibit disruptions to cortico-cerebellar circuits that manifest as difficulties in motor control of the face and limbs. These motor dysfunctions are predictive of the onset and progression of psychosis, making them a potential biomarker for this devastating disease. We examine whether these motor abnormalities disrupt speech production, leading to greater variability in speech acoustics. Clinical high risk (CHR) individuals and matched healthy control (HC) individuals produced diadochokinetic speech (rapid, repeated syllable production, e.g., papapa…, pataka…) and read aloud a paragraph. Consonant and vowel onsets and offsets were automatically segmented from diadochokinetic speech using a deep-learning model trained on human annotators. Read speech was automatically segmented at the word level using forced alignment. Vowel segmentation from read speech was based on forced aligner output; stop consonant onset/offsets were segmented by a deep-learning model. The segmentations from each task were then used to estimate speech rate, voice onset time (VOT), vowel durations and formant trajectories. CHR individuals produced more variable VOTs and exhibited greater speech rate variability than HC individuals in both tasks. This suggests that speech acoustics may provide a window into disruptions in this at-risk population.

Statistical regularities of accented speech influence listeners’ own speech productions

Conversation partners’ speech acoustics sometimes converge, providing evidence for the transfer of information from speech perception to one’s own speech productions. The nature of this phonetic convergence has remained elusive, with variable experimental findings regarding the contexts under which phonetic convergence emerges, the acoustic speech features it affects, and the gender of talkers most influenced. Here, we approach phonetic convergence through the lens of dimension-based statistical learning whereby the statistical regularities of short-term speech input impact the perceptual weight of acoustic dimensions in speech categorization. Participants passively listened to a randomly ordered sequence of 4 pier and 4 beer utterances, sampled across voice onset time (VOT) and fundamental frequency (F0) in a manner that aligned with English norms (Canonical) or departed from typical English pronunciations as an ‘accent’ (Reverse). Immediately after, participants categorized and repeated aloud an ambiguous test stimulus varying only in F0, with ambiguous VOT. The Reverse input regularities led both male and female participants to down-weight F0 in both perceptual categorization and in the acoustics of word repetitions. The results indicate that statistical learning across passive listening to another speaker’s voice can lead to detailed acoustic-phonetic adjustments in one’s own speech productions.

Effect of target word position on use of sentence context in acoustic-hearing listeners to spectrally degraded speech

Understanding of degraded speech can be greatly improved by using sentence context cues. While sentence context effects for sentence-final words are well known, relatively little is known about sentence context effects for sentence-initial words. It is possible that subsequent sentence context can be used to improve understanding of a missed initial word. This study measured phoneme classification of a voice-onset time continuum. The target words from the continuum were presented in one of two sentence locations (beginning, end), and the sentence context cued one target word interpretation (based on phoneme classification) or the other. Acoustic-hearing listeners were presented sentences in clear and spectrally degraded (vocoded) conditions. Preliminary results suggest that sentence context effects are greater when the target word is at the beginning rather than the end of the sentence. We hypothesize that listeners may revise their initial acoustics-based interpretation of the degraded target word based on the sentence context when the target word is first in the sentence, but not when it is last. These location-dependent context effects may interact with individual cognitive skills, such as working memory and processing speed. The data supporting this hypothesis and an analysis of contributing factors (e.g., cognitive skills, age) will be presented.

Acquisition of Voice Onset Time for Voiced Plosives of English by Adult Learners of Balochistan

This study focuses on two experiments conducted with Eastern and Western Balochi speakers. In Eastern Balochi, voiceless stops have aspirated features, but in Western Balochi, they are unaspirated. Eighty-four native speakers of both dialects of Balochi participated in this study. Participants of the first experiment produced words of their L1 in a picture naming task, and those of the second experiment read words in English. VOTs of the L1 and L2 voiced stops elicited from recordings of the productions. Results show that speakers of Western Balochi transfer their L1 negative VOTs to L2 English-voiced stops. However, Eastern Balochi speakers produce English-voiced stops with VOTs, significantly different from their L1 VOTs. Though they could not produce English-voiced stops with native-like accuracy, they produced English stops with significantly longer pre-voicing duration than their L1-voiced stops. Therefore, the study concludes that speakers of those languages with stops with negative VOT ranges face more difficulty acquiring L2 voiced stops of short-lag positive VOTs than those learners whose L1 does not have such stops. The speech learning model is used in this study to analyze all results.

Convergence to shortened and lengthened voice onset time in an imitation task.

Convergence to variation in voice onset time (VOT) of English voiceless stops is reported to be selective, with speakers adjusting their VOTs after exposure to stimuli with lengthened, but not shortened, VOT. The current study re-examined this proposed selectivity with an explicit imitation paradigm designed to maximize convergence, using stimuli with more extreme differences, and explored the perceptual salience of the differences in a discrimination task. Participants showed phonetic convergence to both shortened and lengthened VOT, and better discrimination of shortened than lengthened VOT. Results suggest that there is no general constraint against convergence to shortened VOT.

Deep learning assessment of syllable affiliation of intervocalic consonants.

In English, a sentence like "He made out our intentions." could be misperceived as "He may doubt our intentions." because the coda /d/ sounds like it has become the onset of the next syllable. The nature and occurrence condition of this resyllabification phenomenon are unclear, however. Previous empirical studies mainly relied on listener judgment, limited acoustic evidence, such as voice onset time, or average formant values to determine the occurrence of resyllabification. This study tested the hypothesis that resyllabification is a coarticulatory reorganisation that realigns the coda consonant with the vowel of the next syllable. Deep learning in conjunction with dynamic time warping (DTW) was used to assess syllable affiliation of intervocalic consonants. The results suggest that convolutional neural network- and recurrent neural network-based models can detect cases of resyllabification using Mel-frequency spectrograms. DTW analysis shows that neural network inferred resyllabified sequences are acoustically more similar to their onset counterparts than their canonical productions. A binary classifier further suggests that, similar to the genuine onsets, the inferred resyllabified coda consonants are coarticulated with the following vowel. These results are interpreted with an account of resyllabification as a speech-rate-dependent coarticulatory reorganisation mechanism in speech.

How Good Does This Sound? Examining Listeners’ Second Language Proficiency and Their Perception of Category Goodness in Their Native Language

Language learners often transfer the sounds and prosody of their native language into their second language, but this influence can also flow in the opposite direction, with the second language influencing the first. Among other variables, language proficiency is known to affect the degree and directionality of cross-linguistic influence. However, little is known about how second language learning affects listeners’ perception of their native language. To begin addressing this gap, we examined the relationship between learners’ second language proficiency and their category goodness ratings in their native language. Thirty-nine English-speaking learners of Spanish listened to English words that began with voiced and voiceless stop consonants and were asked to rate how well the word represented the intended word on a 5-point scale. To create a voicing continuum, we manipulated the voice onset time of the word-initial stop in each target item from 125 ms of prevoicing to 100 ms of aspiration, in 25 ms steps. Proficiency did not affect the perception of voiced targets, but both proficiency and L2 stop production affected the perception of voiceless targets.

The acoustic characteristics of implosive and plosive bilabials in Shimaore

Implosive consonants have drawn the attention of researchers over time, partially due to their relative rarity in the world’s languages, and partially due to their unique ingressive air flow. This sound category has varying complex features from an articulatory and acoustic perspective. This study explores the sound category by analyzing the acoustic features of a language whose implosives have yet to be acoustically considered: Shimaore, a Bantu-Sabaki language spoken in Mayotte. Specifically, it compares the bilabial plosive /b/ and the bilabial implosive /ɓ/ in terms of Voice Onset Time (VOT), fundamental frequency, amplitude, and voice quality via H1*–H2*, harmonics-to-noise ratios (HNR), and cepstral peak prominence (CPP). Analyses show that VOT is shorter for implosives than for plosives. At oral closure and vowel onset, amplitude and f0 are higher than plosives. H1*–H2* values read alongside HNR and CPP values suggest that implosives in Shimaore have glottal constriction. Some individual differences are explored for question of variation in implosives. Implications regarding sociophonetic studies in Mayotte as well as general implications for implosives are discussed.

Modelling of Arabic Plosive and Fricative Acoustic Characteristics Articulated by Malay Native Speakers

This study aims to examine the pharyngealized and non-pharyngealized Arabic sounds produced by Malay speakers based on acoustic phonetic approach and to investigate its relation with the second language learning model proposed by Flege (1995). The plosive and fricative associated with the pharyngealized and non-pharyngealized of Arabic sounds is one of the main problems among non-Arabic native speakers in learning Arabic language. Recent studies emphasize the influence of the first language / mother tongue language as the cause of the failure to master the Arabic language as the second language. Hence the frameworks of the similar, different and new sound hypotheses proposed by Flege (1995) were used to get the real picture of the Arabic language speech phenomenon in the second language condition. PRAAT software was used to obtain speech data in the spectrogram and to undergo spectrograph analysis. Subsequently, the findings were analyzed using SPSS to highlight the overall results of the study more thoroughly. VOT (Voice Onset Time) acoustic parameters for the plosive sound and frication of the frication sounds were used during the spectrograph analysis. A total of 2880 spectrogram data were obtained from the subjects: 24 undergraduates from the Bachelor of Islamic Studies with Honors (Arabic Studies and Islamic Civilization) UKM. The results of the production experiment show that Malay plosive sound has negative VOT for voiced stop and short positive VOT for voiceless stop, while Arabic plosive sounds has a model pattern voicing lead versus long lag for voiced and voiceless stops respectively. The results show that Arabic voiceless stop / ت / is aspirated and found to has a longer VOT than Malay voiceless stop /t/. For Arabic pharyngealized sounds, the results show higher values of F1 than non-pharyngealized sounds. In addition, Arabic pharyngealized sounds are found to have shorter VOT than non-pharyngealized Arabic sounds. The findings showed that there were cases where subjects managed to replicate the L2 sound to similar sound of L1 and there were cases of L2 sounds that are foreign to the sound system of L1. With that in mind, it can be emphasized that some studies have supported Flege’s theory that the similar sound between L1 and L2 are not necessarily easy to pronounce, while there are L2 phonemes that are absent in L1, but they are easily learnt by the L2 speaker.

Gender effect on the use of phonetic cues for stops in the Kyungsang dialect

The present study aimed to examine whether there was a gender effect on the phonetic properties of Korean stops in the Kyungsang dialect and investigate how the genders used the acoustic cues across different prosodic positions and focus conditions. Voice onset time, the peak of fundamental frequency, and vowel duration were compared in initial and medial positions of IP and under focused and unfocused conditions. In general, the VOT values of lenis and aspirated stops were shown to be longer for Kyungsang male speakers than for female speakers. The vowel duration, F0 and semitones of the two stops were greater for the female speakers than for the male speakers, and the systematic difference of semitones depending on different prosodic conditions was only found in the speech of the female speakers. While the Kyungsang male speakers made use of VOT to distinguish stop categories, the Kyungsang female speakers put more weight on the use of F0 to contrast the stops across the different prosodic conditions.

제2외국어로서 영어와 한국어 폐쇄음 산출과 인지 연구

This study examines how L1 Korean learners of L2 English and L1 English learners of L2 Korean produce L2 stops in terms of voice onset time (VOT) and fundamental frequency (F0) and how they perceive L2 stops. The study also examines how the level of L2 proficiency functions as a critical factor in determining the L1-to-L2 influence. Two findings were derived from production experiments. First, the primary acoustic cues of L1 stops are negatively transferred to the production of L2 stops in L2 beginners. Second, advanced L2 learners acquire the primary cues of L2 stops. These results indicate that the acquisition of L2 stops is regulated by the different priority order of VOT and F0 between L1 and L2 stops and learners

Characterizing Speech Sound Productions in Bilingual Speakers of Jamaican Creole and English: Application of Durational Acoustic Methods.

This study examined the speech acoustic characteristics of Jamaican Creole (JC) and English in bilingual preschoolers and adults using acoustic duration measures. The aims were to determine if, for JC and English, (a) child and adult acoustic duration characteristics differ, (b) differences occur in preschoolers' duration patterns based on the language spoken, and (c) relationships exist between the preschoolers' personal contextual factors (i.e., age, sex, and percentage of language [%language] exposure and use) and acoustic duration. Data for this cross-sectional study were collected in Kingston, Jamaica, and New York City, New York, United States, during 2013-2019. Participants included typically developing simultaneous bilingual preschoolers (n = 120, ages 3;4-5;11 [years;months]) and adults (n = 15, ages 19;0-54;4) from the same linguistic community. Audio recordings of single-word productions of JC and English were collected through elicited picture-based tasks and used for acoustic analysis. Durational features (voice onset time [VOT], vowel duration, whole-word duration, and the proportion of vowel to whole-word duration) were measured using Praat, a speech analysis software program. JC-English-speaking children demonstrated developing speech motor control through differences in durational patterns compared with adults, including VOT for voiced plosives. Children's VOT, vowel duration, and whole-word duration were produced similarly across JC and English. The contextual factor %language use was predictive of vowel and whole-word duration in English. The findings from this study contribute to a foundation of understanding typical bilingual speech characteristics and motor development as well as schema in JC-English speakers. In particular, minimal acoustic duration differences were observed across the post-Creole continuum, a feature that may be attributed to the JC-English bilingual environment. https://doi.org/10.23641/asha.21760469.

Phonological neighborhood complexity and sound change

Abstract The significance of the phonological neighborhood on lexical processing has been documented by decades of studies in the field, and it has become clear that the phonological connectivity of the mental lexicon is a crucial facilitator for word learning in both the production and perception domains. What has remained underrepresented in the literature to date is the question of how phonological or phonetic changes are accommodated by phonological neighborhoods, or put differently, what the implications of language processing are for language change. The present study investigates how two changes in voice onset time (VOT) in Austrian German onset plosives have appeared in certain types of phonological neighborhoods. Inferences about which phonological neighborhood characteristics are most conducive to sound change are drawn. Results vary by fortis/lenis articulation, with changes in lenis VOT shortening and fortis VOT lengthening being linked to different types of neighborhoods in two different generations of speakers.

Speaking Rate, Oro-Laryngeal Timing, and Place of Articulation Effects on Burst Amplitude: Evidence From English and Tamil.

The relationship between speaking rate and burst amplitude was investigated in plosives with differing oro-laryngeal timing: long-lag voice-onset time (VOT) (North American English) and short-lag VOT (Indian Tamil). Burst amplitude (reflecting both intraoral pressure and flow geometry of the oral channel) was hypothesized to decrease in pre-vocalic plosive syllables with the increase in speaking rate, which imposes temporal constraints on both intraoral pressure buildup behind the oral occlusion and respiratory air flow. The results showed that decreased vowel duration (which is associated with increased speaking rate) led to decreased burst amplitude in both short- and long-lag plosives. Aggregate models of bilabial and velar plosives (found in both languages) suggested lower burst amplitudes in short-lag stops. Place-of-articulation effects in both languages were consistent with models of stop consonant acoustics, and place interactions with vowel duration were most apparent with long-lag English stops. The results are discussed in terms of speaking rate and language-internal forces, contributing to burst amplitude variation and their implications for speech perception and potential to affect lenition phenomena.