Cepstral Changes Following Intensive Voice-Focused Treatment in Parkinson's Disease

The purpose of this study was to analyze cepstral changes following intensive voice-focused treatment in Spanish speakers with Parkinson's disease (PD). A secondary aim of the study was to explore the relationship between cepstral values across time and perceptual data across speech subsystems.

This study followed a one-group pretest-post test design. The smoothed cepstral peak prominence (CPPS) of conversational sentences was analyzed pretreatment and post treatment and at a 1-month follow-up session in 15 Spanish-speaking individuals with PD. A secondary data analysis was then conducted to examine CPPS values relative to perceptual changes in voice quality (VQ), ease of understanding, articulatory precision, resonance (RES), and prosody across time points.

A significant difference in CPPS was established between speakers with mild and moderate dysarthria at pre treatment only. No significant differences were observed between groups at post treatment or follow-up. Within groups, both sets of speakers evidenced significant increases in CPPS post treatment as well as from pre treatment to follow-up. A positive and statistically significant correlation was observed between CPPS scores and the perceptual values for VQ and RES, irrespective of the stage of treatment.

Intensive voice-focused treatment may lead to improved VQ, as measured by the CPPS, in ecologically valid contexts, such as those involving conversations, with gains maintained in the short-term. Additionally, this type of treatment may result in a positive distribution of effects involving not just perceived VQ but also improved perception of RES.