Articulatory Timing Research Articles

Immediate auditory feedback regulates inter-articulator speech coordination in service to phonetic structure.

Research has shown that talkers reliably coordinate the timing of articulator movements across variation in production rate and syllable stress, and that this precision of inter-articulator timing instantiates phonetic structure in the resulting acoustic signal. We here tested the hypothesis that immediate auditory feedback helps regulate that consistent articulatory timing control. Talkers with normal hearing recorded 480 /tV#Cat/ utterances using electromagnetic articulography, with alternative V (/ɑ/-/ɛ/) and C (/t/-/d/), across variation in production rate (fast-normal) and stress (first syllable stressed-unstressed). Utterances were split between two listening conditions: unmasked and masked. To quantify the effect of immediate auditory feedback on the coordination between the jaw and tongue-tip, the timing of tongue-tip raising onset for C, relative to the jaw opening-closing cycle for V, was obtained in each listening condition. Across both listening conditions, any manipulation that shortened the jaw opening-closing cycle reduced the latency of tongue-tip movement onset, relative to the onset of jaw opening. Moreover, tongue-tip latencies were strongly affiliated with utterance type. During auditory masking, however, tongue-tip latencies were less strongly affiliated with utterance type, demonstrating that talkers use afferent auditory signals in real-time to regulate the precision of inter-articulator timing in service to phonetic structure.

Internal speech is faster than external speech: Evidence for feedback-based temporal control

A recent model of temporal control in speech holds that speakers use sensory feedback to control speech rate and articulatory timing. An experiment was conducted to assess whether there is evidence in support of this hypothesis by comparing durations of phrases in external speech (with sensory feedback) and internal speech (without sensory feedback). Phrase lengths were varied by including one to three disyllabic nouns in a target phrase that was always surrounded by overt speech. An inferred duration method was used to estimate the durations of target phrases produced internally. The results showed that internal speech is faster than external speech, supporting the hypothesis. In addition, the results indicate that there is a slow-down associated with transitioning between internal and external modes of production.

Temporal organization of syllables in paced and unpaced speech in children and adolescents who stutter

PurposeSpeaking with an external rhythm has a tremendous fluency-enhancing effect in people who stutter. The aim of the present study is to examine whether syllabic timing related to articulatory timing (c-center) would differ between children and adolescents who stutter and a matched control group in an unpaced vs. a paced condition. MethodsWe recorded 48 German-speaking children and adolescents who stutter and a matched control group reading monosyllabic words with and without a metronome (unpaced and paced condition). Analyses were conducted on four minimal pairs that differed in onset complexity (simple vs. complex). The following acoustic correlates of a c-center effect were analyzed: vowel and consonant compression, acoustic intervals (time from c-center, left-edge, and right-edge to an anchor-point), and relative standard deviations of these intervals. ResultsBoth groups show acoustic correlates of a c-center effect (consonant compression, vowel compression, c-center organization, and more stable c-center intervals), independently of condition. However, the group who stutters had a more pronounced consonant compression effect. The metronome did not significantly affect syllabic organization but interval stability improved in the paced condition in both groups. ConclusionChildren and adolescents who stutter and matched controls have a similar syllable organization, related to articulatory timing, regardless of paced or unpaced speech. However, consonant onset timing differs between the group who stutters and the control group; this is a promising basis for conducting an articulatory study in which articulatory (gestural) timing can be examined in more detail.

Sonority sequencing and its relationship to articulatory timing in Georgian

This work asks how the syllable as a unit is delimited in space and time. To do this we bring together two theoretical approaches to the syllable: a sonority-based approach which emphasizes spatial organization, and the coupled oscillator model (Nam, Goldstein & Saltzman 2009) which emphasizes temporal organization. Many languages present challenges to these theories, and here we focus on Georgian, which is problematic for both approaches, as Georgian permits onset clusters of up to seven consonants and of any sonority shape. Specifically, this study examines the relationship between gestural overlap and sonority shape in Georgian via electromagnetic articulography. Drawing on data from three speakers, we examine gestural overlap in two-consonant onsets that vary in sonority shape and order of place of articulation. Using two measures of gestural overlap, we find (i) long lag between consonant gestures, which we suggest is language-specific and (ii) that lag is largest in sonority rises and smallest in sonority falls. These results suggest that neither phonemic recoverability nor a hierarchical effect of increasingly open constrictions is the primary motivator behind inter-consonantal timing. Instead, the high degree of overlap in sonority falls ensures their tautosyllabic parse, which would otherwise be threatened by intrusive vocoids. Thus, we argue that recoverability of the syllable as a unit is the major motivating factor behind the timing patterns observed, and that syllables emerge not solely from either spatial or temporal properties, but from the interplay of the two.

Differences in speech articulatory timing and associations with pragmatic language ability in autism

BackgroundSpeech articulation difficulties have not traditionally been considered to be a feature of Autism Spectrum Disorder (ASD). In contrast, speech prosodic differences have been widely reported in ASD, and may even be expressed in subtle form among clinically unaffected first-degree relatives, representing the expression of underlying genetic liability. Some evidence has challenged this traditional dichotomy, suggesting that differences in speech articulatory mechanisms may be evident in ASD, and potentially related to perceived prosodic differences. Clinical measurement of articulatory skills has traditionally been phoneme-based, rather than by acoustic measurement of motor control. Subtle differences in articulatory/motor control, prosodic characteristics (acoustic), and pragmatic language ability (linguistic) may each be contributors to differences perceived by listeners, but the interrelationship is unclear. In this study, we examined the articulatory aspects of this relationship, in speech samples from individuals with ASD and their parents during narration. MethodUsing Speechmark® analysis, we examined articulatory landmarks, fine-grained representations of articulatory timing as series of laryngeal and vocal-tract gestures pertaining to prosodic elements crucial for conveying pragmatic information. ResultsResults revealed articulatory timing differences in individuals with ASD but not their parents, suggesting that although potentially not influenced by broader genetic liability to ASD, subtle articulatory differences may indeed be evident in ASD as the recent literature indicates. A follow-up path analysis detected associations between articulatory timing differences and prosody, and subsequently, pragmatic language ability. ConclusionTogether, results suggest a complex relationship where subtle differences in articulatory timing may result in atypical acoustic signals, and serve as a distal mechanistic contributor to pragmatic language ability ASD.

An informal logic of feedback-based temporal control.

A conceptual framework and mathematical model of the control of articulatory timing are presented, in which feedback systems play a fundamental role. The model applies both to relatively small timescales, such as within syllables, and to relatively large timescales, such as multi-phrase utterances. A crucial distinction is drawn between internal/predictive feedback and external/sensory feedback. It is argued that speakers modulate attention to feedback to speed up and slow down speech. A number of theoretical implications of the framework are discussed, including consequences for the understanding of syllable structure and prosodic phrase organization.

Language and cluster-specific effects in the timing of onset consonant sequences in seven languages

In this paper, we draw on available data from previous experiments to explore cross-linguistic variation in articulatory overlap in CC onset clusters, taking into account the role of cluster composition. Our sample includes articulography recordings of eleven clusters for seven languages. We find that cross-linguistic variability is conditional on cluster composition. Previous suggestions that languages may have individual global articulatory timing profiles for consonant clusters in terms of an overall relatively lower or higher degree of overlap are not confirmed for our sample. All included languages converge on a relatively higher degree of overlap for some of the clusters, whereas only some of the languages additionally extend into the lower overlap range, particularly for stop-sonorant sequences. Manner and voicing are further identified as factors conditioning variation in consonantal overlap. Overall languages differ in their degree of overlap in multi-faceted ways, but the relative effects of cluster composition work in the same direction across languages.

Effect of cumulative distance in motor space on segment-sized slips in 3-word phrases

Slips, or speech errors (e.g., “teep a cape” for “keep a tape”), have been described as the disordered arrangement of discrete elements, giving rise to the hypothesis that these arise from misordering during phonological encoding. An alternative hypothesis is that slips are articulatory timing errors, conditioned by the same motor factors that underlie coarticulation. This hypothesis motivates the present study, which used a modified slip procedure to elicit errors from 40 native English-speaking adults. Participants spoke 3-word phrases that were constructed as mini tongue twisters, with alternating word onsets and repeating rhymes. These phrases were designed to condition slips to a greater or less extent according to coarticulatory-adjacent processes (e.g., palatalization). A metric of cumulative distance-traveled in motor space during phrase production was also calculated: the degree of change in vocal tract shapes across the phrase, estimated using data generated within the tubesounds model in ArtiSynth. Phrases designed to more strongly condition slips were expected to cover less cumulative distance in motor space than phrases designed to less strongly condition slips. The distance-traveled metric did not always align with this expectation, but was nonetheless a better predictor of presence/absence of slips than phrase condition in analyses on preliminary data.

The Acquisition of Articulatory Timing for Liquids: Evidence From Child and Adult Speech.

Purpose Liquids are among the last sounds to be acquired by English-speaking children. The current study considers their acquisition from an articulatory timing perspective by investigating anticipatory posturing for /l/ versus /ɹ/ in child and adult speech. Method In Experiment 1, twelve 5-year-old, twelve 8-year-old, and 11 college-aged speakers produced carrier phrases with penultimate stress on monosyllabic words that had /l/, /ɹ/, or /d/ (control) as singleton onsets and /æ/ or /u/ as the vowel. Short-domain anticipatory effects were acoustically investigated based on schwa formant values extracted from the preceding determiner (= the) and dynamic formant values across the /ə#LV/ sequence. In Experiment 2, long-domain effects were perceptually indexed using a previously validated forward-gated audiovisual speech prediction task. Results Experiment 1 results indicated that all speakers distinguished /l/ from /ɹ/ along F3. Adults distinguished /l/ from /ɹ/ with a lower F2. Older children produced subtler versions of the adult pattern; their anticipatory posturing was also more influenced by the following vowel. Younger children did not distinguish /l/ from /ɹ/ along F2, but both liquids were distinguished from /d/ in the domains investigated. Experiment 2 results indicated that /ɹ/ was identified earlier than /l/ in gated adult speech; both liquids were identified equally early in 5-year-olds' speech. Conclusions The results are interpreted to suggest a pattern of early tongue-body retraction for liquids in /ə#LV/ sequences in children's speech. More generally, it is suggested that children must learn to inhibit the influence of vowels on liquid articulation to achieve an adultlike contrast between /l/ and /ɹ/ in running speech.

Fortis-lenis distinction of fricatives and plosives in Welsh – Phonetically distinctive factors

This paper continues a research project aimed at proving that the fortis-lenis distinction is more appropriate for studying the Welsh language than the voiced-voiceless divide. Previous analyses of articulatory timing revealed potentially distinctive features characteristic for Welsh plosives and fricatives. Even though the phonological features such as [spread glottis] or [voice] may be used both for distinguishing between the series of plosives and fricatives, the phonetic features responsible for the distinction are likely to differ due to the different phonetic nature of the manner of articulation and the position of fricatives and plosives (Honeybone 2005: 333–334). The aim of this paper is, therefore, to draw general conclusions from analysing the two sets of factors and find some universal features or characteristics of fortis and lenis obstruents in Welsh. Based on the previous studies, the importance of aspiration and voicing length are analysed in Welsh plosives. For fricatives, friction and voicing length are studied as potentially contrastive. The main hypotheses are that (i) phonetic voicing is not decisive in distinguishing between the two series of sounds in all places of articulation and (ii) other aspects of articulatory timing such as friction, aspiration length and hold phase duration appear to be more important in the fortis-lenis distinction and form a general pattern where the fortis sounds are generally longer than their lenis counterparts.

On the timing and coordination of articulatory movements: Historical perspectives and current theoretical challenges

AbstractThe timing and coordination of articulatory movements is essential to producing speech. A considerable body of literature explores the cognitive and motor control mechanisms involved. This review provides an accessible introduction to that literature, while highlighting articulatory phenomena that challenge prevailing views. We begin with the concept of dynamic articulatory gestures, and their role in the coproduction account of coarticulation. We then outline prominent accounts of gestural coordination. These accounts generally assume that speech planning involves the selection of coarsely grained units, which then unfold involuntarily. Later we consider evidence that speakers rapidly adapt to surprising acoustic feedback, that they plan around the expected timing of upcoming acoustic consequences, and that they reshape the articulatory time course on the fly. These findings suggest that movements can be flexibly modified, and that execution can considerably overlap planning. We advocate for speech models that permit speakers fine‐grained control over unfolding articulation.

Coordination patterns in Essential Tremor patients with Deep Brain Stimulation: Syllables with low and high complexity

This study investigated syllable coordination patterns in Essential Tremor (ET) patients treated with Deep Brain Stimulation (DBS) by using electromagnetic articulography. We analyzed articulatory timing patterns for nine ET patients with activated and inactivated DBS and compared them to a group of healthy age-matched controls. We focused on timing patterns among gestures in syllables with low and high complexity in natural sentence production (simple CV versus complex CCV syllables). These articulatory patterns were interpreted in the framework of a coupled oscillator planning model of speech timing. In simple CV syllables, ET patients did show a similar coordination pattern to healthy control speakers. However, when complexity increased, the patients showed deviant coordination patterns for complex CCV syllables. These deviant patterns even aggravated under activated stimulation. We were able to show that the behavior of the speech system changes when the stimulation was activated, inducing a change in the dynamical system the ET patients have to adapt to. We conclude that coordination problems are not categorical but gradient in nature, pointing to the fact that there are dynamic mechanisms of regulation behind phonetic realization of phonological syllable parses.

Grammatical Word Production Across Metrical Contexts in School-Aged Children's and Adults' Speech.

The purpose of this study is to test whether age-related differences in grammatical word production are due to differences in how children and adults chunk speech for output or to immature articulatory timing control in children. Two groups of 12 children, 5 and 8 years old, and 1 group of 12 adults produced sentences with phrase-medial determiners. Preceding verbs were varied to create different metrical contexts for chunking the determiner with an adjacent content word. Following noun onsets were varied to assess the coherence of determiner-noun sequences. Determiner vowel duration, amplitude, and formant frequencies were measured. Children produced significantly longer and louder determiners than adults regardless of metrical context. The effect of noun onset on F1 was stronger in children's speech than in adults' speech; the effect of noun onset on F2 was stronger in adults' speech than in children's. Effects of metrical context on anticipatory formant patterns were more evident in children's speech than in adults' speech. The results suggest that both immature articulatory timing control and age-related differences in how chunks are accessed or planned influence grammatical word production in school-aged children's speech. Future work will focus on the development of long-distance coarticulation to reveal the evolution of speech plan structure over time.

An electromagnetic articulography study of stop-/s/ and /s/-stop clusters in Greek

Previous kinematic studies on consonant clusters suggest that many factors affect their articulatory timing, including speech rate, frequency of occurrence, and prosody. Other possible factors include the direction of articulatory movement (front-to-back, back-to-front), whether independent articulators (e.g., tongue and lips) or single articulators (e.g., tongue tip and tongue body) are involved, as well as the relative sonority of the consonantal segments. In this study, five talkers of Modern Greek produced the clusters /sp/, /ps/, /sk/, and /ks/ in the carrier phrase “Ipa_______pali” (I said________again). These clusters varied in articulatory direction, articulatory independence, and sonority patterns. We used four methods to determine the degree of articulatory overlap. Each method yielded durations (ms) between gestural landmarks, which were used to compute consonant overlap. The methods differed in the ways gestures were interpreted from the velocity signal (e.g., using extrema or 20% threshold) and how consonant overlap was computed. Preliminary results indicate that articulatory direction and relative sonority exerted the strongest effects on speakers’ productions, while articulator dependence/independence played no apparent role.

The representation and execution of articulatory timing in first and second language acquisition

The early acquisition of language-specific temporal patterns relative to the late development of speech motor control suggests a dissociation between the representation and execution of articulatory timing. The current study tested for such a dissociation in first and second language acquisition. American English-speaking children (5- and 8-year-olds) and Korean-speaking adult learners of English repeatedly produced real English words in a simple carrier sentence. The words were designed to elicit different language-specific vowel length contrasts. Measures of absolute duration and variability in single vowel productions were extracted to evaluate the realization of contrasts (representation) and to index speech motor abilities (execution). Results were mostly consistent with a dissociation. Native English-speaking children produced the same language-specific temporal patterns as native English-speaking adults, but their productions were more variable than the adults’. In contrast, Korean-speaking adult learners of English typically produced different temporal patterns than native English-speaking adults, but their productions were as stable as the native speakers’. Implications of the results are discussed with reference to different models of speech production.

Cross-linguistic differences in articulatory timing lag in consonant cluster perception

Cross-language research on consonant cluster production has shown that consonant clusters in different languages are produced with different degrees of articulatory timing lags. The present study examines perceptual sensitivity to these cross-linguistic timing differences in consonant clusters. Native German listeners were tested on an AXB similarity judgment test using stimuli including consonant clusters produced by German and Georgian speakers. (German consonant clusters are produced with relatively shorter lag between two consonants than Georgian ones.) Stimuli were /bla, gla, gna/ syllables recorded along with articulatory (EMA) data. Short lag German tokens and long lag Georgian tokens were selected as A and B, with Xs of varying degrees of lag chosen from either Georgian or German recordings. Results showed that German listeners are sensitive to the cross-linguistic differences in articulatory timing lag: when the timing lag of X was closer to A, participants were more likely to choose A. Moreover,...

Statistical conversion of silent articulation into audible speech using full-covariance HMM

This article investigates the use of statistical mapping techniques for the conversion of articulatory movements into audible speech with no restriction on the vocabulary, in the context of a silent speech interface driven by ultrasound and video imaging. As a baseline, we first evaluated the GMM-based mapping considering dynamic features, proposed by Toda et al. (2007) for voice conversion. Then, we proposed a ‘phonetically-informed’ version of this technique, based on full-covariance HMM. This approach aims (1) at modeling explicitly the articulatory timing for each phonetic class, and (2) at exploiting linguistic knowledge to regularize the problem of silent speech conversion. Both techniques were compared on continuous speech, for two French speakers (one male, one female). For modal speech, the HMM-based technique showed a lower spectral distortion (objective evaluation). However, perceptual tests (transcription and XAB discrimination tests) showed a better intelligibility of the GMM-based technique, probably related to its less fluctuant quality. For silent speech, a perceptual identification test revealed a better segmental intelligibility for the HMM-based technique on consonants.

Impaired timing adjustments in response to time-varying auditory perturbation during connected speech production in persons who stutter

Auditory feedback (AF), the speech signal received by a speaker’s own auditory system, contributes to the online control of speech movements. Recent studies based on AF perturbation provided evidence for abnormalities in the integration of auditory error with ongoing articulation and phonation in persons who stutter (PWS), but stopped short of examining connected speech. This is a crucial limitation considering the importance of sequencing and timing in stuttering. In the current study, we imposed time-varying perturbations on AF while PWS and fluent participants uttered a multisyllabic sentence. Two distinct types of perturbations were used to separately probe the control of the spatial and temporal parameters of articulation. While PWS exhibited only subtle anomalies in the AF-based spatial control, their AF-based fine-tuning of articulatory timing was substantially weaker than normal, especially in early parts of the responses, indicating slowness in the auditory–motor integration for temporal control.

Articulatory synergies in the temporal organization of liquid clusters in Romanian

This paper investigates on the basis of Romanian EMA data from five speakers which factors may affect the timing of liquid onset and coda clusters. American English /l/-obstruent coda clusters have been shown to pattern differently from obstruent–obstruent clusters. This has been attributed to perceptual constraints influencing articulatory timing relations. However, German codas showed no such differentiation of cluster types, casting doubt on the previously proposed perceptual account. Rather, it may be the lateral's degree of velarization that determines the contrasting patterns between languages. Romanian features, like German, a clear /l/ and a rhotic alveolar trill, allowing us to probe further into the potential role of articulatory synergies by broadening the investigation to liquid clusters generally. Results show that Romanian lateral codas patterned with German, and differently from English. However, Romanian rhotics patterned with the English lateral codas, with which they share a similar tongue rear articulation. We propose that these timing patterns reflect differences in articulatory properties between the various liquid types. Results further show that onset clusters patterned similarly to other onsets in Romanian and across languages. independently of liquid type. We further discuss the interaction of cluster type differences with intra-cluster timing.

A dynamical model of hierarchical selection and coordination in speech planning.

Studies of the control of complex sequential movements have dissociated two aspects of movement planning: control over the sequential selection of movement plans, and control over the precise timing of movement execution. This distinction is particularly relevant in the production of speech: utterances contain sequentially ordered words and syllables, but articulatory movements are often executed in a non-sequential, overlapping manner with precisely coordinated relative timing. This study presents a hybrid dynamical model in which competitive activation controls selection of movement plans and coupled oscillatory systems govern coordination. The model departs from previous approaches by ascribing an important role to competitive selection of articulatory plans within a syllable. Numerical simulations show that the model reproduces a variety of speech production phenomena, such as effects of preparation and utterance composition on reaction time, and asymmetries in patterns of articulatory timing associated with onsets and codas. The model furthermore provides a unified understanding of a diverse group of phonetic and phonological phenomena which have not previously been related.