Effects of an Intensive Voice Treatment on Articulatory Function and Speech Intelligibility in Children with Motor Speech Disorders

Abstract

Producing speech that is clear, audible, and intelligible to others is a challenge for many children with cerebral palsy (CP) and children with Down syndrome (DS). Previous studies have demonstrated the effectiveness of using the Lee Silverman Voice Treatment (LSVT LOUD®) to increase vocal loudness and improve speech intelligibility in individuals with dysarthria secondary to Parkinson’s disease (PD), and some research suggests that it also may be effective for individuals with dysarthria secondary to other conditions, including CP and DS. Although LSVT LOUD only targets vocal loudness, there is some evidence of spreading effects to the articulatory system. Acoustic data from two groups of children with secondary motor speech disorders [one with CP (n= 17) and one with DS (n=9)] who received a full dose of LSVT LOUD and for whom post- treatment intelligibility gains have been previously reported, were analyzed for treatment effects on: 1) vowel triangle area (VTA) and the ratio of F2/i/ to F2/u/); and 2) vowel inherent spectral change (VISC) in the monophthongs /i/, /u/, and /ɑ/. Statistically significant changes in VTA occurred PRE to FUP in the CP group, and increased VTA was observed in 5 of the DS participants. A statistically significant change to VISC for F2/ɑ/ occurred PRE to POST in the CP group. The present study provides evidence of LSVT LOUD treatment spreading effects to the articulatory system in children with CP and children with DS consistent with previous findings in other populations. Limitations of the present study and potential directions for future research are discussed.