Impact of speech rate and mouth opening on hypernasality and speech intelligibility in children with a cleft (lip and) palate

Aim: this study evaluated the effectiveness of different speech techniques (i.e. modification of speech rate and/or mouth opening) for the rehabilitation of hypemasality in children with a cleft palate with or without a cleft lip (CP +/- L). The impact of speech rate and/or mouth opening was investigated on both hypemasality and speech intelligibility. Methods: thirteen patients with CP L and perceived hypemasality (mean age: 10y5m) and 13 age and gender matched children without CP +/- L were included. Children were asked to read an oral and oronasal text passage in ten different speaking conditions where speech rate and/or mouth opening was manipulated. Outcome measures included instrumental measurements of hypernasality and perceptual ratings of speech intelligibility and hypemasality. Results: speaking with a lower speech rate had a statistically significant, positive influence on objective measures of hypemasality in both groups, especially when elicited by a metronome. An increased mouth opening and the combination of both techniques was only effective in the control group. Moreover, it was found that children without CP +/- L were less intelligible when speaking with a decreased mouth opening. Conclusion: a metronome-controlled decrease of speech rate had a positive influence on objective measures of hypemasality both in children with and without CP +/- L. However, present study could not provide any evidence that speaking with increased mouth opening reduces objective and perceptual measures of hypernasality in children with CP +/- L. Further research investigating the use of these techniques is necessary.