Compensatory and adaptive responses to real-time formant shifts in adults and children

Auditory feedback plays an important role in speech motor learning. Previous studies investigating auditory feedback in speech development suggest that crucial steps are made in the development of auditory-motor integration around the age of 4. The present study investigated compensatory and adaptive responses to auditory perturbation in 4 to 9 year-old children compared to young adults (aged 19 – 29 years). Auditory feedback was perturbed by real-time shifting the first and second formant (F1 and F2) of the vowel /e:/ during the production of CVC words in a fivestep paradigm (familiarization; baseline; ramp; hold; release). Results showed that the children were able to compensate and adapt in a similar or larger degree compared to the young adults, even though the proportion of speakers displaying a consistent compensatory response was higher in the group of adults. In contrast to previous reports, results did not show differences in token-to-token variability between children and adults

Auditory feedback perturbation in adults and children

Auditory feedback plays an important role in speech motor learning. Experimental paradigms where auditory feedback is perturbed during speech production of children might give valuable insights in the role of auditory feedback in the acquisition of speech motor programs throughout development. Studies investigating auditory feedback in speech development suggest that crucial steps are made in the development of auditory-motor integration between the ages of 4 – 9 years, but thus far direct comparisons between different age groups are absent. In the present study, we investigated to what extent Dutch speaking children in this age span were able to compensate for and adapt to auditory feedback perturbations. Auditory feedback was perturbed by real-time shifting the first and second formant of the vowel /e/ during the production of CVC words. Preliminary results indicate that age is an important factor in the presence of stable compensation and adaptation effects. When comparing groups, both children and adults were able to compensate for perturbed auditory feedback, but the proportion of subjects displaying this effect was greater in the adult group. Furthermore, we will discuss experimental considerations and limitations of measuring on-line and off-line compensation for perturbed auditory feedback with very young speakers

Articulation in children with developmental speech disorders

A central issue in studies on developmental speech disorders, especially with regard to childhood apraxia of speech (CAS) and phonological disorder (PD) is the distinction between phonological and motoric processes. Acoustic studies suggest that children with CAS produce incorrect realizations of correctly selected phonemes, whereas the opposite is postulated for children with PD. Thus conceived, the underlying impairment is located at different levels of speech production in these two groups of children

A process-oriented approach to differential diagnosis and treatment planning of pediatric speech sound disorders

De classificatie en differentiaaldiagnose van spraakontwikkelingsstoornissen is nog altijd een controversieel thema. De verschillende diagnostische categorieën zijn gedefinieerd op procesniveau, in termen van het cognitieve proces waar de kern van de onderliggende stoornis zich bevindt, en ook de meeste behandelmethoden zijn gericht op verschillende delen van het spraakproductieproces. In de klinische praktijk wordt de differentiaaldiagnose echter gebaseerd op gedragssymptomen, met methoden die bovendien vaak niet gestandaardiseerd en/of genormeerd zijn.Het diagnostische dilemma is dat het onderzoek naar de gedragskarakteristieken van de verschillende subtypes afhankelijk is van ‘zuivere’ casussen geselecteerd op basis van niet-ambigue, helder afgebakende criteria, die echter alleen gedefinieerd en beschikbaar gemaakt kunnen worden als resultaat van onderzoek naar a priori ongedefineerde casussen. In dit paper bespreken we een procesgerichte aanpak van differentiaaldiagnose en indicatiestelling gebaseerd op drie onderzoekslijnen waarmee die circulariteit doorbroken kan worden. De kern van de aanpak bestaat uit drie belangrijke punten/inzichten:Waar gedragssymptomatologie onduidelijk is, is het wel mogelijk om op procesniveau specifieke problemen in deelprocessen helder te definiëren. (Een focus op onderliggende processen in plaats van classificatie op basis van gedragssymptomen.)Processen beïnvloeden elkaar: een stoornis op één procesniveau beïnvloedt het functioneren en de ontwikkeling van andere processen. (Een focus op procesprofielen met gradaties van betrokkenheid.)Spraakproductiesysteem en -stoornis ontwikkelen zich. (Een focus op het veranderen van procesprofielen.)Op basis van deze inzichten opperen we een model van differentiaaldiagnose en therapieplanning voor spraakstoornissen bij kinderen dat ─naast vloeiendheidsstoornis─ bestaat uit twee algemene diagnostische categorieën: spraakachterstand en spraakontwikkelingsstoornis. Binnen deze categorieën worden vervolgens op procesniveau de behandeldoelen geformuleerd. Deze procesgeoriënteerde aanpak van diagnose en therapieplanning heeft belangrijke voordelen. In tegenstelling tot diagnostische classificatie op basis van gedragssymptomen biedt het directe aanknopingspunten voor een dynamisch behandelplan op maat; een behandelplan afgestemd op de specifieke tekortkoming(en) van het individu dat continue wordt geëvalueerd en bijgesteld gedurende het verloop van de spraakstoornis. Aan de hand van een voorbeeld wordt geïllustreerd hoe een dergelijke aanpak er in de praktijk uit kan zien.The classification and differentiation of paediatric speech sound disorders (SSD) remains a controversial issue. The definitions used in classifying childhood SSD and motor speech disorders (MSD) refer to speech production processes, and accordingly a variety of methods of intervention has been developed aiming at different parts of the speech production process. However, diagnosis in clinical practice is primarily based on behavioural speech symptoms rather than the underlying deficits. The diagnostic dilemma is that the ability to investigate the characteristics of subtypes of SSD requires &amp;#39;pure&amp;#39; cases selected on the basis of unambiguous/clear-cut criteria. These criteria can only be defined and made available as a result of research (into a priori undefined /undetermined cases). In this paper we propose a process-oriented approach to diagnosis and treatment planning of paediatric SSD based on three pillars of research that will allow us to break through this circularity. The core of this approach comprises three important notions: 1. Although the behavioural symptomatology of paediatric SSD&amp;#39;s is not completely clear, it is possible to precisely define a specific core problem in terms of processes. (A focus on underlying processing deficits rather than classification based on symptoms.) 2. Developmental interaction between processes: a specific underlying impairment on one level or domain also affects the development on adjacent levels or domains. (A focus on process profiles with degrees of involvement.) 3. The speech production system and -disorder develop/evolve in time. (A focus on changing profiles.) Based on these three notions,we propose a model of differential diagnosis and treatment planning for childhood speech disorders that - besides &amp;quot;fluency disorder&amp;quot; - comprises two general diagnostic categories labelled &amp;quot;speech delay&amp;quot; and &amp;quot;developmental speech disorder&amp;quot;. Within these categories, treatment goals are formulated on the level of processes. This process-oriented approach to diagnosis and treatment planning holds important advantages. In contrast to diagnostic classification based on a description ofbehavioural symptoms, it offers direct leads for treatment aimed at the specific underlying impairment tailored to the specific needs of the individual that is evaluated and adjusted in the course of the speech disorder. The approach is illustrated with an example.</p

Rate-related kinematic changes in younger and older adults

This study aimed to investigate the effects of speech rate changes on kinematic characteristics and stability of speech movements in younger and older speakers using electromagnetic midsagittal articulography (EMMA). Eight young adults and eight older adults engaged in a series of syllable repetition tasks of /pa, /sa/ and /ta/ obtained at self-paced slow, habitual and fast speech rates, as well as in a series of metronome guided speech rates, ranging from 2 to 4 syllables per second. The kinematic parameters duration, amplitude and peak velocity were obtained for opening and closing movements. Older speakers were able to increase speech rate to the same degree or higher compared to younger speakers in both pacing conditions. Kinematic data show that older adults increased duration and decreased peak velocity in closing movements of alveolar constrictions at slower rates more prominently than younger adults. The results on movement stability revealed no differences between age groups. The results suggest that an age-related difference in speed-accuracy trade-off can be ruled out. Differences in kinematic characteristics point towards the possibility that older adults aimed to facilitate a closed loop control system to maintain movement stability at slower speech rates

Stability and composition of functional synergies for speech movements in children and adults

The consistency and composition of functional synergies for speech movements were investigated in 7 year-old children and adults in a reiterated speech task using electromagnetic articulography (EMA). Results showed higher variability in children for tongue tip and jaw, but not for lower lip movement trajectories. Furthermore, the relative contribution to the oral closure of lower lip was smaller in children compared to adults, whereas in this respect no difference was found for tongue tip. These results support and extend findings of non-linearity in speech motor development and illustrate the importance of a multi-measures approach in studying speech motor development

An analysis of speech rate strategies in ageing

Effects of age and speech rate on movement cycle duration were assessed using electromagnetic articulography. In a repetitive task syllables were articulated at eight rates, obtained by metronome and self-pacing. Results indicate that increased speech rate is associated with increasing movement cycle duration stability, while decreased rate leads to a decrease in uniformity of cycle duration, supporting the view that alterations in speech rate are associated with different motor control strategies involving durational manipulations. The relative contribution of closing movement durations increases with decreasing speech rate, and is a more dominant strategy for elderly speakers

Auditory feedback perturbation in children with developmental speech sound disorders

Several studies indicate a close relation between production symptoms and perceptual acuity in children with speech sound disorders (SSD). An important underlying factor here might be a reduced capacity to use auditory feedback. However, the mechanisms behind this relation are still poorly understood. The aim of this study was to investigate the ability to compensate and adapt for perturbed auditory feedback in children with SSD compared to age-matched normally developing children (age 4-8) to unravel the role of auditory feedback in the manifestation of SSD. 15 normally developing children aged 4.1-8.7 years (mean=5.5, SD=1.4), and 11 children with SSD aged 3.9-7.5 years (mean=5.1, SD=1.0) participated in the study. Auditory feedback was perturbed by real-time shifting the first and second formant of the vowel /e/ during the production of CVC words in a five-step paradigm (familiarization; baseline; ramp; hold; release). Preliminary results indicate a larger proportion of subjects responding to perturbation in children with SSD compared to the control group. However, in general the normally developing children showing a response were better able to compensate and adapt, adjusting their formant frequencies in the direction opposite to the perturbation where the majority of the children with SSD followed (amplifying) the perturbation

Speech rate strategies in younger and older adults

Several studies have indicated a general decrease in speed and accuracy of speech output in older compared to younger speakers. In a previous study investigating reiterated productions of syllables /pa/, /sa/ and /ta/ at different speech rates, we found that older adults when slowing down, more prominently increased duration and decreased peak velocity in closing movements compared to younger adults. As a possible explanation we proposed that older adults may evidence a mechanism that facilitates a closed loop control system to maintain movement stability, possibly due to a reduced quality of somatosensory input. In the present study, we examined this phenomenon further using a reiterated speech task with target words /a:pi/ and /ipa:/, which regarding jaw and lips, involve three-step movement schemes consisting respectively of one closing and two opening movements and two closing and one opening movement. Eight young adults and eight elderly speakers participated in the study. Articulographic data were collected on the reiterated productions of the target words at self-paced slow, habitual and fast speech rates, and in a series of metronome guided speech rates ranging from 2 to 4 syllables per second. Results will be presented at the conference