Background: The motor speech disorder, dysarthria, is common in cerebral palsy. The Speech Systems Approach therapy programme, which focuses on controlling breath supply and speech rate, has increased children’s intelligibility.
Objective: To ascertain if increased intelligibility is due to better differentiation of the articulation of individual consonants in words spoken in isolation and in connected speech.
Design: Secondary analysis.
Setting: University.
Participants: Forty-two children with cerebral palsy and dysarthria aged 5–18 years, Gross Motor Function Classification System I–V.
Intervention: The Speech Systems Approach is a motor learning therapy delivered to individuals by a speech and language therapist in 40-minute sessions, three times per week for 6 weeks. Intervention focuses on production of a strong, clear voice and speaking at a steady rate. Practice changes from single words to increasingly longer utterances in tasks with increasing cognitive load.
Main outcome measures:
Unfamiliar listeners’ identification of singleton consonants (e.g.
Data sources: Data collected at 1-week pre- and 1-week post-therapy from three studies: two interrupted time series design, one feasibility randomised controlled trial.
Results: Word initial and word final singleton consonants and consonant clusters were better identified post-therapy. The extent of improvement differed across word initial and word final singleton consonant subtypes. Improvement was greater for single words than connected speech. Change in sound identification varied across children, particularly in connected speech. Sound intensity and duration increases also were inconsistent.
Limitations: The small sample size did not allow for analysis of cerebral palsy type. Acoustic data were not available for all children, limiting the strength of conclusions that can be drawn. The different but phonetically balanced word lists, used in the original research, created variability in single words spoken across recordings analysed. Low frequencies of plosives, fricatives and affricates necessitated their combination for analysis preventing investigation of the effect of specific consonants. Connected speech was spontaneous, again creating variability within the data analysed. The estimated effects of therapy may therefore be partially explained by differences in the spoken language elicited.
Conclusions: The Speech Systems Approach helped children generate greater breath supply and a steady rate, leading to increased intensity and duration of consonant sounds in single words, thereby aiding their identification by listeners. Transfer of the motor behaviour to connected speech was inconsistent.
Future work: Refining the Speech Systems Approach to focus on connected speech early in the intervention. Personalisation of cues according to perceptual and acoustic speech measures. Creation of a battery of measures that can be repeated across children and multiple recordings.
Study registration: This trial is registered as Research Registry 6117.
Funding: This project was funded by the National Institute for Health and Care Research (NIHR) Efficacy and Mechanism Evaluation programme (NIHR130967) and will be published in full in Efficacy and Mechanism Evaluation; Vol. 10, No. 4. See the NIHR Journals Library website for further project information.
Some children with cerebral palsy have speech that sounds weak, slurred and difficult to understand, which seriously impacts their social life and education. We developed a therapy programme to help children control their breathing and how fast they speak. Having more breath should make children’s voices stronger. Speaking at a steady rate should give enough time for children to move their jaw, tongue and lips to produce each sound more precisely. Children’s speech was easier to understand after the therapy. This study aimed to find out if the therapy worked by helping children to say consonant sounds more clearly.
We used recordings made in previous research to work out which consonants listeners heard correctly. We also looked at waveforms, which showed children’s speech as moving pictures, to find out how speech changed.
After therapy, when children spoke in single words, listeners heard almost all types of consonant sounds at the start and end of words more clearly. No particular type of consonant sounds, such as ‘s’ in ‘so’ or ‘t’ in ‘tar’, led to better speech clarity. Waveforms showed that some children produced stronger speech sounds, some slowed their speech, and some did both.
Listeners heard some children more clearly after therapy when they spoke in phrases, but found others more difficult to understand. Few consonants were easier to understand after therapy. We saw no clear patterns of change in speech waveforms.
Overall, children produced stronger, more precise speech in single words, but not all transferred this skill to speaking in phrases. Children differed in how they achieved clearer speech.
We used the findings to refine the therapy to focus on phrases early in the programme and to personalise instructions to children’s individual speech patterns. We will use waveforms to find where children have most difficulty and to measure improvement.
Copyright © 2023 Pennington et al.