Speech glottal flow performance in early stages of Parkinson's disease and multiple systems atrophy

The speech phonation subsystem has been widely studied for assessing phonatory impairments in the presence of numerous pathologies, especially neurodegenerative diseases. Perturbation or/and cepstral measures have been the traditional acoustic features for this purpose. However, these measures have the drawback of involving all the speech production subsystems. To isolate the phonatory component, analysis of the glottal flow generated by the vibration of the vocal folds is an appealing alternative. However, despite its significant pertinence, this approach has been relatively little studied. In this paper, we conducted the first study of glottal flow performance in the setting of atypical parkinsonian disorders. Our main objective was the identification of distinctive glottal features that can assist in the challenging problem of early differential diagnosis between Parkinson's disease (PD) and the parkinsonian variant of multiple systems atrophy (MSA-P). In addition to the traditional sustained phonation task, we analyzed short vowel production in diadochokinesis (DDK) tasks, using a classical method for the estimation and parameterization of the glottal flow. The results showed that the DDK task was valuable towards revealing MSA-P specific glottal disruptions. Moreover, contrarily to other studies, our results suggested that patients with early-stage PD do not manifest glottal flow impairment.