Speech power spectra: a window into neural oscillations in Parkinson's disease

This study analyzes the power spectral density (PSD) of speech in healthy controls (HC) and Parkinson's disease (PD) patients, focusing on the 0-100 Hz range. These low frequency components are below the fundamental frequency and may reflect both motor and neural mechanisms in speech production. We hypothesize that neural oscillations (NOs) involved in speech perception and production - theta (4-8 Hz), beta (15-35 Hz), and gamma (36-80 Hz) - shape the low-frequency PSD. Since NOs are linked to motor control and cognition, and are altered in PD, we expect systematic differences between HC and PD speech. Using multitaper estimation, we found significant differences in beta power, in line with research on beta oscillations and motor dysfunction in PD. Beyond distinguishing HC from PD speech, our results suggest that sub-fundamental frequency information may reflect neural dynamics in speech production, offering new perspectives for speech pathology and neural oscillation research.