Speech and voice disorders in Parkinson's disease

Aim. To examine the voice, speech dysfunction and acoustic parameters typically associated with Parkinson's disease (PD), including the effects on respiration, phonation, articulation and prosody; the effect of treatment with the drug levodopa and deep brain stimulation of the subthalamic nucleus is also examined. Development. One of the features of PD is the alteration of voice and speech. The motor deficits associated with PD adversely affect the major systems that govern speech motor control including respiration, phonation, and articulation. The speech deficits related to PD are often called hypokinetic dysarthria and can be characterized by monopitch, monoloudness, reduced stress, imprecise consonants, and inappropriate silences. Numerous studies have documented these changes using a wide variety of acoustic measures. Conclusions. Acoustic correlates of PD have a potential to provide useful biomarkers and sensitive methods for the early detection of the onset, progression, and severity of disease states, as well as providing a means to objectively track symptomatic changes and to assess the efficacy of pharmacological and surgical treatments.