Frits van Brenk

Auditory feedback perturbation in children with developmental speech sound disorders

BACKGROUND/PURPOSE Several studies indicate a close relation between auditory and speech motor functions in children with speech sound disorders (SSD). 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. METHOD 17 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 (practice/familiarization; start/baseline; ramp; hold; end/release). RESULTS At the group level, the normally developing children were better able to compensate and adapt, adjusting their formant frequencies in the direction opposite to the perturbation, while the group of children with SSD followed (amplifying) the perturbation. However, large individual differences lie underneath. Furthermore, strong correlations were found between the amount of compensation and performance on oral motor movement non-word repetition tasks. CONCLUSIONS Results suggested that while most children with SSD can detect incongruencies in auditory feedback and can adapt their target representations, they are unable to compensate for perturbed auditory feedback. These findings suggest that impaired auditory-motor integration may play a key role in SSD. LEARNING OUTCOMES The reader will be able to: (1) describe the potential role of auditory feedback control in developmental speech disorders (SSD); (2) identify the neural control subsystems involved in feedback based speech motor control; (3) describe the differences between compensation and adaptation for perturbed auditory feedback; (4) explain why auditory-motor integration may play a key role in SSD.

Rate-Related Kinematic Changes in Younger and Older Adults

Aims: 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. Patients and Methods: Eight young adults and 8 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. Results: 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. Conclusions: 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.