The relation between acoustic and articulatory variation in vowels : data from American and Australian English

In studies of dialect variation, the articulatory nature of vowels is sometimes inferred from formant values using the following heuristic: F1 is inversely correlated with tongue height and F2 is inversely correlated with tongue backness. This study compared vowel formants and corresponding lingual articulation in two dialects of English, standard North American English and Australian English. Five speakers of North American English and four speakers of Australian English were recorded producing multiple repetitions of ten monophthongs embedded in the /sVd/ context. Simultaneous articulatory data were collected using electromagnetic articulography. Results show that there are significant correlations between tongue position and formants in the direction predicted by the heuristic but also that the relations implied by the heuristic break down under specific conditions. Articulatory vowel spaces, based on tongue dorsum (TD) position, and acoustic vowel spaces, based on formants, show systematic misalignment due in part to the influence of other articulatory factors, including lip rounding and tongue curvature on formant values. Incorporating these dimensions into our dialect comparison yields a richer description and a more robust understanding of how vowel formant patterns are reproduced within and across dialects

Consonant Context Effects on Vowel Sensorimotor Adaptation

Speech sensorimotor adaptation is the short-term learning of modified articulator movements evoked through sensory-feedback perturbations. A common experimental method manipulates acoustic parameters, such as formant frequencies, using real time resynthesis of the participant\u27s speech to perturb auditory feedback. While some studies have examined phrases comprised of vowels, diphthongs, and semivowels, the bulk of research on auditory feedback-driven sensorimotor adaptation has focused on vowels in neutral contexts (/hVd/). The current study investigates coarticulatory influences of adjacent consonants on sensorimotor adaptation. The purpose is to evaluate differences in the adaptation effects for vowels in consonant environments that vary by place and manner of articulation. In particular, we addressed the hypothesis that contexts with greater intra-articulator coarticulation and more static articulatory postures (alveolars and fricatives) offer greater resistance to vowel adaptation than contexts with primarily inter-articulator coarticulation and more dynamic articulatory patterns (bilabials and stops). Participants completed formant perturbation-driven vowel adaptation experiments for varying CVCs. Results from discrete formant measures at the vowel midpoint were generally consistent with the hypothesis. Analyses of more complete formant trajectories suggest that adaptation can also (or alternatively) influence formant onsets, offsets, and transitions, resulting in complex formant pattern changes that may reflect modifications to consonant articulatio

Bias and consistency of individual lingual articulatory behavior and its relationship to the first and second formants

Individual variation in articulatory behavior can be characterized by bias and consistency in movement outcome. Consistency can be indicated by variable error (VE) representing precision of individual performance and bias by constant error (CE) representing tendency in movement outcome. The present study employs CE and VE to characterize individual articulatory behavior, and assesses the relationship between consistency and bias in the articulatory and acoustic domains. We computed CE and VE of tongue blade and dorsum kinematic trajectories and the first two formants’ curves in the production of /æ/ and /ɑ/ by 20 native U.S. English speakers. The relationship between acoustic and kinematic VE and CE were revealed using gradient boosting machines. Results indicate that individual CE and VE vary over the time course of a vowel and that movement outcome is affected by linguistic constraints

Asymmetric discrimination of non-speech tonal analogues of vowels

Published in final edited form as: J Exp Psychol Hum Percept Perform. 2019 February ; 45(2): 285–300. doi:10.1037/xhp0000603.Directional asymmetries reveal a universal bias in vowel perception favoring extreme vocalic articulations, which lead to acoustic vowel signals with dynamic formant trajectories and well-defined spectral prominences due to the convergence of adjacent formants. The present experiments investigated whether this bias reflects speech-specific processes or general properties of spectral processing in the auditory system. Toward this end, we examined whether analogous asymmetries in perception arise with non-speech tonal analogues that approximate some of the dynamic and static spectral characteristics of naturally-produced /u/ vowels executed with more versus less extreme lip gestures. We found a qualitatively similar but weaker directional effect with two-component tones varying in both the dynamic changes and proximity of their spectral energies. In subsequent experiments, we pinned down the phenomenon using tones that varied in one or both of these two acoustic characteristics. We found comparable asymmetries with tones that differed exclusively in their spectral dynamics, and no asymmetries with tones that differed exclusively in their spectral proximity or both spectral features. We interpret these findings as evidence that dynamic spectral changes are a critical cue for eliciting asymmetries in non-speech tone perception, but that the potential contribution of general auditory processes to asymmetries in vowel perception is limited.Accepted manuscrip

Neuromechanical Modelling of Articulatory Movements from Surface Electromyography and Speech Formants

Speech articulation is produced by the movements of muscles in the larynx, pharynx, mouth and face. Therefore speech shows acoustic features as formants which are directly related with neuromotor actions of these muscles. The first two formants are strongly related with jaw and tongue muscular activity. Speech can be used as a simple and ubiquitous signal, easy to record and process, either locally or on e-Health platforms. This fact may open a wide set of applications in the study of functional grading and monitoring neurodegenerative diseases. A relevant question, in this sense, is how far speech correlates and neuromotor actions are related. This preliminary study is intended to find answers to this question by using surface electromyographic recordings on the masseter and the acoustic kinematics related with the first formant. It is shown in the study that relevant correlations can be found among the surface electromyographic activity (dynamic muscle behavior) and the positions and first derivatives of the first formant (kinematic variables related to vertical velocity and acceleration of the joint jaw and tongue biomechanical system). As an application example, it is shown that the probability density function associated to these kinematic variables is more sensitive than classical features as Vowel Space Area (VSA) or Formant Centralization Ratio (FCR) in characterizing neuromotor degeneration in Parkinson's Disease.This work is being funded by Grants TEC2016-77791-C4-4-R from the Ministry of Economic Affairs and Competitiveness of Spain, Teka-Park 55 02 CENIE-0348_CIE_6_E POCTEP (InterReg Programme) and 16-30805A, SIX Research Center (CZ.1.05/2.1.00/03.0072), and LO1401 from the Czech Republic Government

Modelling English diphthongs with dynamic articulatory targets

The nature of English diphthongs has been much disputed. By now, the most influential account argues that diphthongs are phoneme entities rather than vowel combinations. However, mixed results have been reported regarding whether the rate of formant transition is the most reliable attribute in the perception and production of diphthongs. Here, we used computational modelling to explore the underlying forms of diphthongs. We tested the assumption that diphthongs have dynamic articulatory targets by training an articulatory synthesiser with a three-dimensional (3D) vocal tract model to learn English words. An automatic phoneme recogniser was constructed to guide the learning of the diphthongs. Listening experiments by native listeners indicated that the model succeeded in learning highly intelligible diphthongs, providing support for the dynamic target assumption. The modelling approach paves a new way for validating hypotheses of speech perception and production

Vowel Production in Down Syndrome: An Ultrasound Study

The present study investigated the articulatory and acoustic characteristics of vowel production in individuals with Down syndrome (DS). Speech production deficits and reduced intelligibility are consistently noted in this population, attributed to any combination of phonological, structural, and/or motor control deficits. Speakers with DS have demonstrated impaired vowel production, as indicated by perceptual, acoustic, and articulatory data, with emerging evidence of vowel centralization. Participants in the study included eight young adults with DS, as well as eight age- and gender-matched controls. Ultrasound imaging was utilized to obtain midsagittal tongue contours during single-word productions, specifically targeting the corner vowels /ɑ/, /æ/, /i/, and /u/. Measurements of tongue shape, as related to its curvature and vowel differentiation, were calculated and contrasted between the participant groups. Acoustic measures of vowel centralization and variability of production were applied to concurrent vowel data. Single-word intelligibility testing was also conducted for speakers with DS, to obtain intelligibility scores and for analysis of error patterns. Results of the analyses demonstrated consistent differentiation for low vowel production between the two speaker groups, across both articulatory and acoustic measures. Speakers with DS exhibited reduced tongue shape curvature and/or complexity of low vowels /ɑ/ and /æ/, and high-vowel /u/, than did TD speakers, as well as some evidence of reduced differentiation between tongue shapes of all four corner vowels. Acoustic analysis revealed a lack of group differentiation across some metrics of vowel centralization, while a reduction in acoustic space dispersion from a centroid was demonstrated for the low vowels in speakers with DS. Increased variability of acoustic data was also noted among speakers in the DS group in comparison to TD controls. Single-word intelligibility scores correlated strongly with measures of acoustic variability among speakers with DS, and moderately with measures of articulatory differentiation. Clinical implications, as related to understanding the nature of the impairment in DS and effective treatment planning, are discussed

Model-based exploration of linking between vowel articulatory space and acoustic space

While the acoustic vowel space has been extensively studied in previous research, little is known about the high-dimensional articulatory space of vowels. The articulatory imaging techniques are limited to tracking only a few key articulators, leaving the rest of the articulators unmonitored. In the present study, we attempted to develop a detailed articulatory space obtained by training a 3D articulatory synthesizer to learn eleven British English vowels. An analysis-by-synthesis strategy was used to acoustically optimize vocal tract parameters that represent twenty articulatory dimensions. The results show that tongue height and retraction, larynx location and lip roundness are the most perceptually distinctive articulatory dimensions. Yet, even for these dimensions, there is a fair amount of articulatory overlap between vowels, unlike the fine-grained acoustic space. This method opens up the possibility of using modelling to investigate the link between speech production and perception

Monitorización de la enfermedad de Parkinson a partir de la cinemática de la articulación del habla

Parkinson Disease (PD) is a neuromotor illness affecting general movements of different muscles, those implied in speech production being among them. The relevance of speech in monitoring illness progression has been documented in these last two decades. Most of the studies have concentrated in dysarthria and dysphonia induced by the syndrome. The present work is devoted to explore how PD affects the dynamic behavior of the speech neuromotor biomechanics (neuromechanics) involved in deficient articulation (dysarthria), in contrast to classical measurements based on static features as extreme and central vowel triangle positions. A statistical distribution of the kinematic velocity of the lower jaw and tongue is introduced, which presents interesting properties regarding pattern recognition and classification. This function may be used to establish distances between different articulation profiles in terms of information theory. Results show that these distances are correlated with a set of tests currently used by neurologists in PD progress evaluation, and could be used in elaborating new speech testing protocols.La enfermedad de Parkinson (EP) es un trastorno del sistema neuromotor que afecta a todo tipo de movimientos regulados por el sistema muscular humano, entre ellos los que controlan la producción del habla. La importancia del habla en la monitorización del progreso de la EP se ha estudiado ampliamente durante las últimas dos décadas. La mayoría de los estudios se han concentrado en describir y modelar el comportamiento de la fonación (disfonía) y de la articulación (disartria), en relación con el síndrome de la EP. El presente trabajo se centra en explorar la forma en la que la EP afecta al comportamiento dinámico de la biomecánica neuromotora relacionada con la disartria típica mostrada por este tipo de pacientes, a diferencia de las mediciones clásicamente utilizadas hasta el momento, que se basan en las posiciones extremas y centrales del triángulo vocálico. Se propone, para ello, una nueva medida basada en la distribución estadística de la cinemática del sistema mandibular y lingual, que presenta interesantes propiedades de cara al reconocimiento de patrones utilizado en la clasificación de los rasgos disártricos del paciente. Esta medida puede emplearse para establecer las distancias entre las distintas articulaciones en términos de la teoría de información. Los resultados del estudio presentado muestran que dichas distancias se hallan sustancialmente correlacionadas con ciertas pruebas utilizadas habitualmente por los neurólogos para evaluar el progreso de la EP. La distancia cinemática propuesta puede servir para elaborar nuevos protocolos de realización de pruebas para el seguimiento de la EP