Effects of Rate Manipulation on Intelligibility in Children With Cerebral Palsy

Abstract

Purpose We evaluated the effects of a speech supplementation strategy to reduce rate and improve intelligibility in children with cerebral palsy. Method Twenty-five children with cerebral palsy (M _age = 12.08 years) completed a structured speaking task in 2 speech conditions: habitual speech and slow speech. Fifteen children had mild intelligibility deficits; 10 had moderate-severe intelligibility deficits. In each condition, children repeated utterances of 2-7 words in length. In the habitual speech condition, children used their natural and unaltered speaking rate. In the slow speech condition, children were cued to insert pauses between words. Intelligibility ratings were obtained from orthographic transcriptions by unfamiliar adult listeners (n = 100). Speech rate, in words per minute, was measured for each utterance. Results All children, regardless of severity group, were able to reduce their rate of speech when implementing the slow speech strategy. Only children in the moderate-severe group showed an improvement in intelligibility when implementing the slow speech strategy. Although there was considerable individual variability, there was a greater improvement in intelligibility for longer utterances compared to shorter ones. Conclusion A slow speech strategy may be beneficial for children with moderate-severe intelligibility deficits who speak in longer utterances. Future studies should seek to further examine the clinical feasibility of slow speech for children with reduced intelligibility.

Figure 1.

Example of a display for a five-word utterance during the habitual speech condition.

Figure 2.

Example of a cueing display for four-word utterances. At the beginning of the task, all cells are blank. Children touch each cell, and a picture related to the prompted word appears in the cell.

Figure 3.

Example of a cueing display for three-word utterances. Children touch each cell, and a picture related to the prompted word appears in the cell.

Figure 4.

Changes in rate (words per minute) and intelligibility (percentage of words identified correctly) from the habitual speech condition to the slow speech condition for children in the mild severity group (green) and the moderate–severe group (orange). Thick lines represent group means, thin lines represent individual children, and arrows are used to visualize the change from the habitual condition to the slow condition.

Figure 5.

Changes in rate (words per minute) and intelligibility (percentage of words identified correctly) from the habitual speech condition to the slow speech condition by utterance length for children in the mild severity group (green) and the moderate–severe group (orange). Thick lines represent group means, thin lines represent individual children, and arrows are used to visualize the change from the habitual condition to the slow condition. Points without lines are cases where a child completed the task for the utterance length in only one of the speech conditions. These points do not contribute to the plotted means.