Acoustic changes in the speech of children with cerebral palsy following an intensive program of dysarthria therapy*

Abstract

Background: The speech intelligibility of children with dysarthria and cerebral palsy has been observed to increase following therapy focusing on respiration and phonation. Aims: To determine if speech intelligibility change following intervention is associated with change in acoustic measures of voice. Methods & Procedures:We recorded 16 young people with cerebral palsy and dysarthria (nine girls; mean age 14 years, SD = 2; nine spastic type, two dyskinetic, four mixed; one Worster-Drought) producing speech in two conditions (single words, connected speech) twice before and twice after therapy focusing on respiration, phonation and rate. In both single-word and connected speech we measured vocal intensity (root mean square-RMS), period-to-period variability (Shimmer APQ, Jitter RAP and PPQ) and harmonics-to-noise ratio (HNR). In connected speech we also measured mean fundamental frequency, utterance duration in seconds and speech and articulation rate (syllables/s with and without pauses respectively). All acoustic measures were made using Praat. Intelligibility was calculated in previous research. Outcomes & Results:In single words statistically significant but very small reductions were observed in period-toperiod variability following therapy: Shimmer APQ -0.15 (95% CI = -0.21 to -0.09); Jitter RAP -0.08 (95% CI = -0.14 to -0.01); Jitter PPQ -0.08 (95% CI = -0.15 to -0.01). No changes in period-to-period perturbation across phrases in connected speech were detected. However, changes in connected speech were observed in phrase length, rate and intensity. Following therapy, mean utterance duration increased by 1.11 s (95% CI = 0.37-1.86) when measured with pauses and by 1.13 s (95% CI = 0.40-1.85) when measured without pauses. Articulation rate increased by 0.07 syllables/s (95% CI = 0.02-0.13); speech rate increased by 0.06 syllables/s (95% CI = < 0.01-0.12); and intensity increased by 0.03 Pascals (95% CI = 0.02-0.04). There was a gradual reduction in mean fundamental frequency across all time points . Only increases in the intensity of single words (0.37 Pascals, 95% CI = 0.10-0.65) and reductions in fundamental frequency (-0.11 Hz, 95% CI = -0.21 to -0.02) in connected speech were associated with gains in intelligibility. Conclusions & Implications:Mean reductions in impairment in vocal function following therapy observed were small and most are unlikely to be clinically significant. Changes in vocal control did not explain improved intelligibility.

Views of children with cerebral palsy and their parents on the effectiveness and acceptability of intensive speech therapy

“…As louder speech is generated from increased breath support, the greater air volumes could also support longer utterances. The changes reported here are the perceptual correlates of the change in acoustic measures found in previous studies [9,[27][28][29]. The reports of children generalizing their new speech patterns to conversation outside the therapy environment and their articulation of strategies also suggest that motor learning has taken place and new behaviours can be produced when needed [13].…”

“…Nevertheless, C6's parents described increases in her intelligibility in real life exchanges and greater communicative participation. Increases in intelligibility and participation without change in speech function have been observed in previous studies [11,27]. This lack of coupling between speech impairment and intelligibility suggests that the mechanism of change is more complex than an increase in speech function engendering increased intelligibility prompting increased participation, and that some other mechanism is at work.…”

Effects of speech cues in French‐speaking children with dysarthria

“…2013, Pennington et al . 2010, 2013, 2018). As a result, speech–language pathologists in francophone environments have a weak research base from which to guide their treatment strategies for improving French‐speaking children's communication.…”

“…Most treatment studies on childhood dysarthria, with research advanced primarily by Pennington and colleagues (e.g., Pennington et al . 2018), target various subsystems to improve speech production. This research has found increased duration of breath groups, for example, following a subsystems‐based approach.…”

Longitudinal Change in Speech Rate and Intelligibility Between 5 and 7 Years in Children With Cerebral Palsy

“…The finding of consistent change in speech development for children with SMI through the age of 7 years may have promising implications for treatment. Targeted therapies such as those employed by Pennington and colleagues (Pennington, Lombardo, Steen, & Miller, 2018;Pennington, Miller, Robson, & Steen, 2010;Pennington, Roelant, et al, 2013) that are specific to speech motor profiles, such as those identified by Allison (Allison & Hustad, 2018b), may be particularly beneficial when children are in periods of enhanced growth.…”