How fluent is the fluent speech of people who stutter? A new approach to measuring kinematics with ultrasound

AM deposited 2020-06-22We present a new approach to the investigation of dynamic ultrasound tongue imaging (UTI) data, applied here to analyse the subtle aspects of the fluency of people who stutter (PWS). Fluent productions of CV syllables (C = /k/; V = /, i, /) from three PWS and three control speakers (PNS) were analysed for duration and peak velocity relative to articulatory movement towards (onset) and away from (offset) the consonantal closure. The objective was to apply a replicable methodology for kinematic investigation to speech of PWS in order to test Wingate's Fault-Line hypothesis. As was hypothesised, results show comparable onset behaviours for both groups. Regarding offsets, groups differ in peak velocity. Results suggest that PWS do not struggle initiating consonantal closure (onset). In transition from consonantal closure into the vowel, however, groups appear to employ different strategies expressed in increased variation (PNS) versus decreased mean peak velocity (PWS).casl30pub4219pub3-

Back from the future:Nonlinear anticipation in adults and children's speech

Purpose: This study examines the temporal organization of vocalic anticipation in German children from 3 to 7 years of age and adults. The main objective was to test for non-linearprocesses in vocalic anticipation, which may result from the interaction between lingualgestural goalsfor individual vowels, and those for their neighbors over time. Method: The technique of ultrasound imaging was employed to record tongue movement at fivetimepoints throughout short utterances of the form V1#CV2. Vocalic anticipation was examined with Generalized Additive Modeling, an analytical approach allowing forthe estimation of both linear and non-linearinfluences on anticipatoryprocesses. Results: both adults and children exhibit non-linear patterns of vocalic anticipation over time with the degree and extent of vocalic anticipation varying as a function of the individual consonants and vowels assembled. However, noticeable developmental discrepancieswere found with vocalic anticipation being present earlier in children ́sutterances at 3-4-5 years of agein comparison to adults and to some extent 7-year-old children.Conclusions: Anarrowing of speech production organization from large chunks in kindergarten to more contextually-specified organizationsseems to occur fromkindergarten toprimary school toadulthood, although variation in the temporal overlap of lingual gestures for consecutive segments is already present in the youngestcohorts. In adults, non-linear anticipatory patterns over time suggest a strong differentiation between the gestural goals for consecutive segments. In children, this differentiation is not yet mature: vowelsshow greater prominence over time and seem activated more in-phase with those of previous segments relative to adults

AN ARTICULATORY-ACOUSTIC INVESTIGATION OF TIMING AND COORDINATION IN THE FLUENT SPEECH OF PEOPLE WHO STAMMER

This thesis investigates Wingate’s Fault-Line hypothesis (1988) which suggests that disfluencies in people who stammer (PWS) result from a deficit in transition from consonant to vowel (CV) thereby implying that stammering as a motor-control disorder would affect transitions even when not perceptually salient. To test this proposal, we explored the perceptually fluent speech of PWS using instrumental analysis (ultrasound and acoustic) to determine the underlying pervasiveness of disfluencies in this group as compared to people who do not stammer (PNS). Following fluency screening of recorded utterances, we applied acoustic and articulatory analysis techniques to perceptually fluent utterances of 9 PWS and 9 typical speakers in order to identify indicators of disfluency in the transition from syllable onsets to the following vowel. Measures of acoustic duration, locus equation and formant slope offer insights into timing and degree of coarticulation. The articulatory ultrasound tongue imaging technique moreover provides kinematic information of the tongue. A novel technique was applied to dynamically analyse and quantify the tongue kinematics in transition. This allowed us to treat the perceptually fluent speech of PWS as an ongoing time-situated process. Both acoustic and articulatory findings indicate by-group differences in timing, whereby PWS are overall slower and more variable in the execution of CV transitions when compared to typical speakers (PNS). The findings from both instrumental approaches also indicate differences in coordination, suggesting that PWS coarticulate to a lesser extent than PNS. Overall, these findings suggest that PWS exhibit a global deficit in CV transition that can be observed in perceptually fluent as well as stammered speech. This is in keeping with the predictions of Wingate’s Fault-Line hypothesis. iv The fact that the conclusions from the acoustic and articulatory measures are coherent, shows that acoustic measures may be sufficient to act as a proxy for articulatory measures

Covert contrast and covert errors in persistent velar fronting

Special Issue on Covert ContrastsThis is an Accepted Manuscript of an article published by Taylor & Francis in Clinical Linguistics & Phonetics on 09/09/2016, available online: https://doi.org/10.1080/02699206.2016.1209788Acoustic and articulatory studies demonstrate covert contrast in perceptually neutralised phonemic contrasts in both typical children and children with speech disorders. These covert contrasts are thought to be relatively common and symptomatic of phonetic speech disorders. However, clinicians in the speech therapy clinic have had no easy way of identifying this covertness. This study uses ultrasound tongue imaging to compare tongue contours for /t/and /k/in seven children with persistent velar fronting. We present a method of overlaying tongue contours to identify covert contrast at the articulatory level. Results show that all seven children, contrary to expectations, produced both /t/and /k/with near-identical tongue shapes showing no evidence of covert contrast. However, further analysis of one of the participants showed highly variable tongue shapes for /t/and /k/, including retroflex productions of both. Although not phonologically conditioned, this covert error is evidence of speech disorder at the phonetic level.This work was funded by grants EP/I027696/1(Engineering and Physical Sciences Research Council, UK) and ETM/402 (Chief Scientist Office, Scotland).casl31pub4523pub

Three speech sounds, one motor action: Evidence for speech-motor disparity from English flap production

The assumption that units of speech production bear a one-to-one relationship to speech motor actions pervades otherwise widely varying theories of speech motor behavior. This speech produc- tion and simulation study demonstrates that commonly occurring flap sequences may violate this assumption. In the word “Saturday,” a sequence of three sounds may be produced using a single, cyclic motor action. Under this view, the initial upward tongue tip motion, starting with the first vowel and moving to contact the hard palate on the way to a retroflex position, is under active muscular control, while the downward movement of the tongue tip, including the second contact with the hard palate, results from gravity and elasticity during tongue muscle relaxation. This sequence is reproduced using a three-dimensional computer simulation of human vocal tract biomechanics and differs greatly from other observed sequences for the same word, which employ multiple targeted speech motor actions. This outcome suggests that a goal of a speaker is to produce an entire sequence in a biomechanically efficient way at the expense of maintaining parity within the individual parts of the sequence

Vowel variability and contrast in Childhood Apraxia of Speech: acoustics and articulation

none5noPhoneme production may be affected by limited speech motor control in Childhood Apraxia of Speech (CAS), with a general instability of acoustic targets across multiple repetitions of speech stimuli. This acoustic and Ultrasound Tongue Imaging (UTI) study shows that increased variability and reduction of contrast in vowel production is found in native Italian speakers with CAS, particularly as far as the height dimension is concerned. The data suggest that vowel production should play a major role in CAS diagnosis and treatment. Moreover, this study shows that a combined acoustic and articulatory approach allows direct observation of lingual dynamics together with an estimation of changes in the acoustic dimension. The two dimensions are shown not to correspond in a straightforward way in the speech of children with CAS, and encourage consideration of articulatory compensation strategies aimed at saving the acoustic identity of vowels.openLenoci, Giovanna; Celata, Chiara; Ricci, Irene; Chilosi, Anna; Barone, VincenzoLenoci, Giovanna; Celata, Chiara; Ricci, Irene; Chilosi, Anna; Barone, Vincenz