Impact of the LSVT on vowel articulation and coarticulation in Parkinson’s disease

Abstract

The purpose of this study was to investigate the impact of the Lee Silverman Voice Treatment (LSVT®) on vowel articulation and consonant–vowel (C–V) coarticulation in dysarthric speakers with Parkinson’s disease (PD). Nine Quebec French speakers diagnosed with idiopathic PD underwent the LSVT®. Speech characteristics were compared before and after treatment. Vowel articulation was measured using acoustic vowel space and calculated with the first (F1) and second formant (F2) of the vowels /i/, /u/ and /a/. C–V coarticulation was measured using locus equations, an acoustic metric based on the F2 transitions within vowels in relation to the preceding consonant. The relationship between these variables, speech loudness and vowel duration was also analysed. Results showed that vowel contrast increased in F1/F2 acoustic space after administration of the LSVT®. This improvement was associated with the gain in speech loudness and longer vowel duration. C–V coarticulation patterns between consonant contexts showed greater distinctiveness after the treatment. This improvement was associated with the gain in speech loudness only. These results support the conclusions of previous studies investigating the relationship between the LSVT®, speech loudness and articulation in PD. These results expand clinical understanding of the treatment and indicate that loud speech changes C–V coarticulation patterns. Clinical applications and theoretical considerations are discussed.

• Acoustic analysis
• articulation
• dysarthria
• Parkinson’s disease
• treatment

Acknowledgements

The authors thank Monica Lavoie for her assistance with administering the treatment, Noémie Auclair-Ouellet for the dysarthria diagnoses, and Sonia Routhier, Marie-Christine Veilleux and Marie-Hélène Fortier for their assistance with the recording sessions and analyses.

Declaration of interest

The authors report no conflicts of interest.

This study was supported by a doctoral grant from the Fonds de Recherche Société et Culture du Québec.