Affiliations: Neuropsychology Research Unit, Psychology Department,
Monash University, Clayton 3168, Victoria, Australia | Kingston Centre, Warrigal Road, Cheltenham 3192,
Victoria, Australia
Note: [] Corresponding author: Aileen K. Ho, Department of Psychology,
Monash University, Clayton 3168, Victoria, Australia. Tel.: +61 3 9755 5616;
Fax: +61 3 9905 3948; E-mail: Aileen.Ho@sci.monash.edu.au
Abstract: This study classified speech impairment in 200 patients with
Parkinson's disease (PD) into five levels of overall severity and described the
corresponding type (voice, articulation, fluency) and extent (rated on a
five-point scale) of impairment for each level. From two-minute conversational
speech samples, parameters of voice, fluency and articulation were assessed by
two trained-raters. Voice was found to be the leading deficit, most frequently
affected and impaired to a greater extent than other features in the initial
stages. Articulatory and fluency deficits manifested later, articulatory
impairment matching voice impairment in frequency and extent at the `Severe'
stage. At the final stage of `Profound' impairment, articulation was the most
frequently impaired feature at the lowest level of performance. This study
illustrates the prominence of voice and articulatory speech motor control
deficits, and draws parallels with deficits of motor set and motor set
instability in skeletal controls of gait and handwriting.
