Diphthong productions in speakers with Parkinson’s disease across speaking modes

Abstract

Several vowel acoustics parameters (e.g., second formant frequency (F2) slope, vowel space area) are known to significantly contribute to speech intelligibility in dysarthria (Kim, Kent, Weismer, 2011; Lansford & Liss, 2014). Particularly, F2 slope has been identified as an important predictor of speech intelligibility regardless of underlying neuropathologies of dysarthria (Kim, Weismer, Kent & Duffy, 2009). The current study focuses on intra-speaker modifications of F2 slope in speakers with Parkinson’s disease (PD) voluntarily elicited across three speaking modes, less clear, conversational, and more clear speech, in recognition that prior work has mostly focused on inter-speaker comparisons. Varying speech clarity was our interest, given its wide use as an efficient behavioral therapeutic approach in clinic. Twenty speakers (10 PD, 10 neurologically healthy) were asked to read diphthongs embedded in real words. Diphthongs were chosen because they require a significant change in configuration of vocal tract and, therefore, are sensitive to the presence/severity of dysarthria. In the presentation, distributions of F2 slope 1) between PD and healthy speakers, and 2) across speaking modes within each speaker will be discussed. In addition, articulatory data will be presented for part of the speakers from whom kinematic data were obtained using the electromagnetic articulography (EMA) system.