Syllable Production Research Articles

Aerodynamic Threshold Measures for Reflecting Glottal Closure in Voice Disorders.

Previous work suggested that phonation threshold pressure (PTP), phonation threshold flow (PTF), and phonation threshold power (PTW) could be effective aerodynamic measures for quantifying glottal incompetence. This study examined how these measures could reflect varying extent of incomplete glottal closure in individuals with voice disorders. Thirty individuals formally diagnosed with glottal incompetence, including 10 with hypofunctional disorders (hypo group) and 20 with hyperfunctional disorders (hyper group), and 30 individuals with normal voice (control group) participated in the study. PTP was measured indirectly by intra-oral pressure during production of bilabial stop consonant-vowel syllables, PTF was measured during the sustained vowel /a/, and PTW was obtained as the product of PTP and PTF. The extent of incomplete glottal closure was quantified by normalized glottal gap (NGG) and normalized glottal gap area (NGGA) based on image analysis of videostroboscopic recordings of sustained /i/. Significant differences in all threshold measures (p < .05) were found among three participant groups with medium-to-large effect sizes (ηp2 = .128-.220), with significantly higher values for the hypo group than the control group and no significant differences between the hyper and control groups. Receiver operating characteristic (ROC) analysis showed the highest diagnostic or classification accuracy contrasting between the hypo and control groups (area under the ROC curve = .717-.757), with the highest classification accuracy for PTW. There were significant, moderate-to-strong positive correlations with NGG and NGGA for the disorders group (Pearson's r = .4244-.6226) and the hypo group (r = .5689-.8949). These measures could be effective for identifying glottal incompetence, especially for hypofunctional disorders. PTW could be more sensitive than PTP and PTF in reflecting the extent of incomplete glottal closure, consistent with theoretical predictions. Their relative sensitivities for quantifying distinct incomplete glottal closures specific to different voice disorders should be evaluated in future studies.

Robotic assistants for the rehabilitation of communication disorders in children: A proposal based on MTO manufacturing for developing countries

Language is fundamental to human communication, allowing individuals to express and exchange ideas, thoughts, and emotions. In early childhood, some children experience communication disorders that impede their ability to articulate words correctly, posing significant challenges to their learning and development. This issue is exacerbated in developing countries, where limited resources and a lack of technological tools hinder access to effective speech therapy. Traditional speech therapy remains vital, but the latest technological advancements have introduced robotic assistants to enhance therapy for communication disorders. Despite their potential, these technologies are often inaccessible in developing regions due to high production costs and a lack of sustainable manufacturing models. For these reasons, this paper presents “FONA,” a robotic assistant that employs rule-based expert systems to provide tactile, auditory, and visual stimuli. FONA supports children aged 3 to 6 in speech therapy by delivering exercises such as syllable production, word formation, and pictographic storytelling of various phonemes. Notably, FONA was successfully tested on children with cochlear implants, reducing the number of sessions required to produce isolated phonemes. The paper also introduces an innovative analysis of the Make To Order (MTO) manufacturing system for producing FONA in developing countries. This analysis explores two key perspectives: collaborative networks and entrepreneurship, offering a sustainable production model. In a pilot experiment, FONA significantly improved children’s attention spans, increasing the period by 17 min. Furthermore, the economic analysis demonstrates that producing FONA through collaborative networks can significantly reduce costs, making it more accessible to institutions in developing countries. The findings suggest that the project is viable for a five-year period, providing a sustainable and effective solution for addressing communication disorders in children.

Enhancing analysis of diadochokinetic speech using deep neural networks

Diadochokinetic speech tasks (DDK) involve the repetitive production of consonant-vowel syllables. These tasks are useful in detecting impairments, differential diagnosis, and monitoring progress in speech-motor impairments. However, manual analysis of those tasks is time-consuming, subjective, and provides only a rough picture of speech. This paper presents several deep neural network models working on the raw waveform for the automatic segmentation of stop consonants and vowels from unannotated and untranscribed speech. A deep encoder serves as a features extractor module, replacing conventional signal processing features. In this context, diverse deep learning architectures, such as convolutional neural networks (CNNs) and large self-supervised models like HuBERT, are applied for the extraction process. A decoder model uses derived embeddings to identify frame types. Consequently, the paper studies diverse deep architectures, ranging from linear layers, LSTM, CNN, and transformers. These architectures are assessed for their ability to detect speech rate, sound duration, and boundary locations on a dataset of healthy individuals and an unseen dataset of older individuals with Parkinson’s Disease. The results reveal that an LSTM model performs better than all other models on both datasets and is comparable to trained human annotators.

Optimization of classifying accurate and misarticulated speech sounds for use in a gamified real-time ultrasound biofeedback system

Integrating ultrasound biofeedback therapy (UBT) into a real-time, gamified interface to provide articulatory feedback for speech remediation promotes an external focus of attention, thereby reducing the complex cognitive demands required for standard UBT. Previous studies have shown that accuracy of American English rhotic /r/ can be predicted by a single parameter, the difference between tongue dorsum and blade displacements measured by ultrasound imaging during speech production. This parameter has classified speech productions of rhotic syllables as correct versus misarticulated with a classification accuracy up to 85%. However, implementation of this classification approach into real-time gamified UBT, including both measurement timing and establishment of difficulty levels for progressive therapy, would benefit from optimization using a larger dataset. 2,450 productions of 10 distinct rhotic syllables (including prevocalic and postvocalic contexts) from 50 children, with and without misarticulations, were analyzed. For each production, ultrasound image sequences were processed by TonguePART software to acquire tongue displacement trajectories, and accuracy was judged by trained listeners using a visual analog scale. Analyses were conducted to optimize selection of the image frame for classification, determine parameter thresholds appropriate for real-time prediction of /r/ production accuracy, and integrate these thresholds into a difficulty level design for gamified UBT.

Features of animal babbling in the vocal ontogeny of the gray mouse lemur (Microcebus murinus)

In human infants babbling is an important developmental stage of vocal plasticity to acquire maternal language. To investigate parallels in the vocal development of human infants and non-human mammals, seven key features of human babbling were defined, which are up to date only shown in bats and marmosets. This study will explore whether these features can also be found in gray mouse lemurs by investigating how infant vocal streams gradually resemble the structure of the adult trill call, which is not present at birth. Using unsupervised clustering, we distinguished six syllable types, whose sequential order gradually reflected the adult trill. A subset of adult syllable types was produced by several infants, with the syllable production being rhythmic, repetitive, and independent of the social context. The temporal structure of the calling bouts and the tempo-spectral features of syllable types became adult-like at the age of weaning. The age-dependent changes in the acoustic parameters differed between syllable types, suggesting that they cannot solely be explained by physical maturation of the vocal apparatus. Since gray mouse lemurs exhibit five features of animal babbling, they show parallels to the vocal development of human infants, bats, and marmosets.

Lateralization and Time-Course of Cortical Phonological Representations during Syllable Production.

Spoken language contains information at a broad range of timescales, from phonetic distinctions on the order of milliseconds to semantic contexts which shift over seconds to minutes. It is not well understood how the brain's speech production systems combine features at these timescales into a coherent vocal output. We investigated the spatial and temporal representations in cerebral cortex of three phonological units with different durations: consonants, vowels, and syllables. Electrocorticography (ECoG) recordings were obtained from five participants while speaking single syllables. We developed a novel clustering and Kalman filter-based trend analysis procedure to sort electrodes into temporal response profiles. A linear discriminant classifier was used to determine how strongly each electrode's response encoded phonological features. We found distinct time-courses of encoding phonological units depending on their duration: consonants were represented more during speech preparation, vowels were represented evenly throughout trials, and syllables during production. Locations of strongly speech-encoding electrodes (the top 30% of electrodes) likewise depended on phonological element duration, with consonant-encoding electrodes left-lateralized, vowel-encoding hemispherically balanced, and syllable-encoding right-lateralized. The lateralization of speech-encoding electrodes depended on onset time, with electrodes active before or after speech production favoring left hemisphere and those active during speech favoring the right. Single-electrode speech classification revealed cortical areas with preferential encoding of particular phonemic elements, including consonant encoding in the left precentral and postcentral gyri and syllable encoding in the right middle frontal gyrus. Our findings support neurolinguistic theories of left hemisphere specialization for processing short-timescale linguistic units and right hemisphere processing of longer-duration units.

Disentangling Effects of Memory Storage and Inter-articulator Coordination on Generalization in Speech Motor Sequence Learning.

Generalization in motor control is the extent to which motor learning affects movements in situations different than those in which it originally occurred. Recent data on orofacial speech movements indicates that motor sequence learning generalizes to novel syllable sequences containing phonotactically illegal, but previously practiced, consonant clusters. Practicing an entire syllable, however, results in even larger performance gains compared to practicing just its clusters. These patterns of generalization could reflect language-general changes in phonological memory storage and/or inter-articulator coordination during motor sequence learning. To disentangle these factors, we conducted two experiments in which talkers intensively practiced producing novel syllables containing illegal onset and coda clusters over two consecutive days. During the practice phases of both experiments, we observed that, through repetition, talkers gradually produced the syllables with fewer errors, indicative of learning. After learning, talkers were tested for generalization to single syllables (Experiment 1) or syllable pairs (Experiment 2) that overlapped to varying degrees with the practiced syllables. Across both experiments, we found that performance improvements from practicing syllables with illegal clusters partially generalized to novel syllables that contained those clusters, but performance was more error prone if the clusters occurred in a different syllable position (onset versus coda) as in practice, demonstrating that inter-articulator coordination is contextually sensitive. Furthermore, changing the position of a cluster was found to be more deleterious to motor performance during the production of the second syllables in syllable pairs, which required talkers to store more phonological material in memory prior to articulation, compared to single syllables. This interaction effect reveals a complex interplay between memory storage and inter-articulator coordination on generalization in speech motor sequence learning.

Looking within events: Examining internal temporal structure with local relative rate

This paper describes a method for quantifying temporally local variation in the relative rates of speech signals, based on warping curves obtained from dynamic time warping. Although the use of dynamic time warping for signal alignment is well established in speech science, its use to estimate local rate variation is quite rare. Here we introduce an extension of the local relative rate method that supports the quantification of variability in local relative rate, both within and across a set of events. We show how measures of temporal variation derived from this analysis method can be used to characterize the internal temporal structure of events. In order to achieve this, we first provide an overview of the standard dynamic time warping algorithm. We then introduce the local relative rate measure and describe our extensions, applying them to an articulatory and acoustic dataset of consonant-vowel-consonant syllable productions.

Neural speech tracking shifts from the syllabic to the modulation rate of speech as intelligibility decreases.

The most prominent acoustic features in speech are intensity modulations, represented by the amplitude envelope of speech. Synchronization of neural activity with these modulations supports speech comprehension. As the acoustic modulation of speech is related to the production of syllables, investigations of neural speech tracking commonly do not distinguish between lower-level acoustic (envelope modulation) and higher-level linguistic (syllable rate) information. Here we manipulated speech intelligibility using noise-vocoded speech and investigated the spectral dynamics of neural speech processing, across two studies at cortical and subcortical levels of the auditory hierarchy, using magnetoencephalography. Overall, cortical regions mostly track the syllable rate, whereas subcortical regions track the acoustic envelope. Furthermore, with less intelligible speech, tracking of the modulation rate becomes more dominant. Our study highlights the importance of distinguishing between envelope modulation and syllable rate and provides novel possibilities to better understand differences between auditory processing and speech/language processing disorders.

The initiation of a hand grip is delayed by silently reading an incompatible syllable.

The movements of phonation structures (e.g., tongue) have been shown to facilitate compatible hand movements. For example, reaction time (RT) of precision and power hand grips (made with tips of thumb and finger vs. whole hand) are shortened with the production of syllables that share similar action features (e.g., employing the proximal vs. dorsal portion of the tongue, respectively). This effect is coined the articulation-grip correspondence (AGC) effect. However, it is not known if the AGC effect is due to action facilitation vs. interference, and if such facilitation/ interference is due to covertly or overtly reading the syllable. To answer the associated empirical questions, the present experiment involved participants initiating a precision or power grip without the covert/ overt reading of a syllable, or while covertly or overtly reading the syllable /ti/ or /ka/. In both the covert and overt reading conditions, there were longer RTs for precision grips with the syllable /ka/ than /ti/, and there were longer RTs for power grips with the syllable /ti/. In contrast, the syllable /ti/ or /ka/ did not alter precision or power grip RTs, respectively. These findings support the notion of articulation-grip interference but not facilitation and that such interference can be observed with covert (silent) reading.

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.

An Acoustic Study on The Effects Intonation Imposes on Sentence-final Particles in Nanjing Dialect

To investigate the interaction between tone and intonation on the production of the sentence-final syllables and the effects of a specific type of characters, i.e. sentence-final particles (SFPs) in Nanjing dialect, acoustic analyses were carried out in the current study. Participants were asked to produce sentences under four conditions: (1) SFPs in interrogative sentences; (2) SFPs in declarative sentences; (3) homophones of the SFPs in interrogative sentences; (4) homophones of the SFPs in declarative sentences. The acoustic productions were analyzed in order to compare the same SFPs in different intonation patterns, i.e., interrogatives and declaratives, and SFPs and their homophones in the carrier sentences. Results showed that the influence of intonation on tones within sentence-final syllables indeed exists, but SFPs mitigate the extent to which intonation functions. These results suggest that intonation is present in tonal languages as well, whereas SFPs influence the realization of intonation by reducing the extent of global rising.

Utilidad del índice diadococinético DDKCVP% para la detección de imprecisiones articulatorias en enfermedad de Parkinson: estudio exploratorio preliminar

ABSTRACT Purpose: to explore whether the diadochokinetic index of syllable production variability (DDKcvp%) is useful for the detection of articulatory inaccuracies in different stages of Parkinson's disease (PD). Methods: a diadochokinetic speech task of the consonant-vowel type [pa-pa-pa] was applied to 18 people with PD (classified in stages of progression from 1 to 5 according to the Hoehn &amp; Yahr scale) to determine their diadochokinetic performance. Records of the study group were compared to a reference value obtained from a control group made up of 40 subjects. Results: 77.78% of the study group showed articulatory inaccuracies. The DDKcvp% index allowed to detect articulatory difficulties from stage 1 of PD, and its variation showed that articulatory deficits were permanent from stage 2 onwards. A significant and direct correlation was obtained between the increase in the DDKcvp% index and the increase in the stage of evolution of the participants. Conclusion: DDKcvp% index evaluated by means of a simple and fast consonant-vowel diadochokinetic task [pa-pa-pa], could be useful to determine articulatory inaccuracies in different stages of PD, although it is suggested that investigation of this index in larger sample sizes be conducted.

Consonant Perception in Connected Syllables Spoken at a Conversational Syllabic Rate.

Closed-set consonant identification, measured using nonsense syllables, has been commonly used to investigate the encoding of speech cues in the human auditory system. Such tasks also evaluate the robustness of speech cues to masking from background noise and their impact on auditory-visual speech integration. However, extending the results of these studies to everyday speech communication has been a major challenge due to acoustic, phonological, lexical, contextual, and visual speech cue differences between consonants in isolated syllables and in conversational speech. In an attempt to isolate and address some of these differences, recognition of consonants spoken in multisyllabic nonsense phrases (e.g., aBaSHaGa spoken as /ɑbɑʃɑɡɑ/) produced at an approximately conversational syllabic rate was measured and compared with consonant recognition using Vowel-Consonant-Vowel bisyllables spoken in isolation. After accounting for differences in stimulus audibility using the Speech Intelligibility Index, consonants spoken in sequence at a conversational syllabic rate were found to be more difficult to recognize than those produced in isolated bisyllables. Specifically, place- and manner-of-articulation information was transmitted better in isolated nonsense syllables than for multisyllabic phrases. The contribution of visual speech cues to place-of-articulation information was also lower for consonants spoken in sequence at a conversational syllabic rate. These data imply that auditory-visual benefit based on models of feature complementarity from isolated syllable productions may over-estimate real-world benefit of integrating auditory and visual speech cues.

Impaired neural entrainment to low frequency amplitude modulations in English-speaking children with dyslexia or dyslexia and DLD

Neural synchronization to amplitude-modulated noise at three frequencies (2 Hz, 5 Hz, 8 Hz) thought to be important for syllable perception was investigated in English-speaking school-aged children. The theoretically-important delta-band (∼2Hz, stressed syllable level) was included along with two syllable-level rates. The auditory steady state response (ASSR) was recorded using EEG in 36 7-to-12-year-old children. Half of the sample had either dyslexia or dyslexia and DLD (developmental language disorder). In comparison to typically-developing children, children with dyslexia or with dyslexia and DLD showed reduced ASSRs for 2 Hz stimulation but similar ASSRs at 5 Hz and 8 Hz. These novel data for English ASSRs converge with prior data suggesting that children with dyslexia have atypical synchrony between brain oscillations and incoming auditory stimulation at ∼ 2 Hz, the rate of stressed syllable production across languages. This atypical synchronization likely impairs speech processing, phonological processing, and possibly syntactic processing, as predicted by Temporal Sampling theory.

How we speak when we speak to a beat: The influence of temporal coupling on phonetic enhancement

Stressed syllables in languages which have them tend to show two interesting properties: They show patterns of phonetic ‘enhancement’ at the articulatory and acoustic levels, and they also show coordinative properties. They typically play a key role in coordinating speech with co-speech gesture, in coordination with a musical beat, and in other sensorimotor synchronization tasks such as speech-coordinated beat tapping and metronome timing. While various phonological theories have considered stress from both of these perspectives, there is as yet no clear explanation as to how these properties relate to one another. The present work tests the hypothesis that aspects of phonetic enhancement may in fact be driven by coordination itself by observing how phonetic patterns produced by speakers of two prosodically-distinct languages—English and Medʉmba (Grassfields Bantu)—vary as a function of timing relations with an imaginary metronome beat. Results indicate that production of syllables in time (versus on the ‘offbeat’) with the imaginary beat led to increased duration and first formant frequency—two widely observed correlates of syllable stress—for speakers of both languages. These results support the idea that some patterns of phonetic enhancement may have their roots in coordinative practices.&amp;nbsp;

Early Development of Syllable Structure in French

ABSTRACT Cross-linguistic studies describing the syllabic structures of babbling productions agree on the high prevalence of the CV structure, but few have addressed the other types of syllables emerging during this pre-linguistic stage. However, studying the evolution of the distribution of syllabic structures during babbling would make it possible to test both the influence of motor constraints and the influence of the perceptually based patterns from the infant’s language environmental input on the production of early syllables. A monthly follow-up of 22 French infants from 8 to 14 months showed that the distribution CV>V> CCV>CVC>VC was shared by the majority of infants in the sample and remained the same throughout the observation period. The comparison of the frequencies of the structures observed with those attested in adult-French and in 4 other languages (Dutch, Korean, Moroccan Arabic and Tunisian Arabic) revealed significant differences between all adult samples and infant productions. The results have implications for understanding the nature of factors impacting syllable production at the babbling stage. We discuss the possibility that the target language does not affect the production of babbled syllables.

Transcranial direct current stimulation over the primary motor cortex improves speech production in post-stroke dysarthric speakers: A randomized pilot study.

PurposeThe current study investigated the therapeutic potential of transcranial direct current stimulation (tDCS) on speech intelligibility, speech-related physiological and vocal functions among post-stroke dysarthric patients.MethodNine chronic post-stroke dysarthric patients were randomly assigned to the stimulation or sham group. The stimulation group received 2mA of anodal tDCS over the left inferior primary motor cortex for 15 minutes, while the sham group received 30s of stimulation under the same settings. All the participants received 10 daily 15 minutes of individualized speech therapy targeting their dominant phonological process or phonemes with the greatest difficulty. The outcome measures included (1) perceptual analysis of single words, passage reading and diadochokinetic rate, (2) acoustic analysis of a sustained vowel, and (3) kinematic analysis of rapid syllable repetitions and syllable production in sentence, conducted before and after the treatment.ResultsThe results revealed that both the stimulation and sham groups had improved perceptual speech intelligibility at the word level, reduced short rushes of speech during passage reading, improved rate during alternating motion rate, AMR-kha1, and improved articulatory kinematics in AMR-tha1 and syllables /tha1/ and /kha1/ production in sentence. Compared to the sham group, the stimulation group showed significant improvement in articulatory kinematics in AMR-kha1 and syllable /kha1/ production in sentence. The findings also showed that anodal stimulation led to reduced shimmer value in sustained vowel /a/ phonation, positive changes in articulatory kinematics in AMR-tha1 and syllables /pha1/ and /kha1/ production in sentence at the post treatment measure. In addition to positive effects on articulatory control, reduced perturbation of voice amplitude documented in the stimulation group post treatment suggests possible tDCS effects on the vocal function.ConclusionsThe current study documented the beneficial effects of anodal tDCS over the primary motor cortex on speech production and suggested that combined tDCS and speech therapy may promote recovery from post-stroke dysarthria.

Syllable complexity in 24-month-old infants resulting from spontaneous mother–child vocal interactions

Infant Directed Speech (IDS) influences language development via caregiver–child interactions and can promote early speech and language outcomes in some cultures (Golinkoff et al., 2015). IDS is characterized by a higher, more dynamic fundamental frequency (f0) as well as shorter caregiver utterances and simplified phono-lexical structures (Ramirez-Esparza et al., 2014). In line with social feedback theories of early vocal development (Warlaumont et al. 2014), this study proposes that certain acoustic aspects of IDS, when produced contingently with infant speech, will promote infants’ early vocal maturity. N = 84 infant-caregiver dyads were recorded during semi-naturalistic play sessions at 7, 10, 18, and 24 months. Infant vocal maturity was quantified as syllable complexity at 24-months where syllables with consonant-vowel (CV or VC) transitions were more complex than syllables with only a nucleus (V). The complexity of children’s syllables produced within 5 sof contingent caregiver speech will be compared to those produced outside of 5-swindows of caregiver speech. Infants’ syllable production will also be related to acoustic characteristics of IDS including f0 height, modulation, and caregiver speaking rate. Positive correlations between IDS characteristics and infant syllable complexity will provide additional evidence that socially contingent IDS spurs early speech development.

Neural mechanisms for turn-taking in duetting plain-tailed wrens.

Recent studies conducted in the natural habitats of songbirds have provided new insights into the neural mechanisms of turn–taking. For example, female and male plain–tailed wrens (Pheugopedius euophrys) sing a duet that is so precisely timed it sounds as if a single bird is singing. In this review, we discuss our studies examining the sensory and motor cues that pairs of wrens use to coordinate the rapid alternation of syllable production. Our studies included behavioral measurements of freely–behaving wrens in their natural habitat and neurophysiological experiments conducted in awake and anesthetized individuals at field sites in Ecuador. These studies show that each partner has a pattern-generating circuit in their brain that is linked via acoustic feedback between individuals. A similar control strategy has been described in another species of duetting songbird, white–browed sparrow–weavers (Plocepasser mahali). Interestingly, the combination of neurophysiological results from urethane-anesthetized and awake wrens suggest a role for inhibition in coordinating the timing of turn–taking. Finally, we highlight some of the unique challenges of conducting these experiments at remote field sites.