However, average speaking fundamental frequencies show considerable inter-speaker and intra-speaker differences due to intentional prosodic changes ( Atkinson, 1976). Some studies have found higher mean F0 values in individuals with Parkinsonian voice ( Goberman & Blomgren, 2008), particularly in males ( Canter, 1963 Holmes et al., 2000 Metter & Hanson, 1986 Skodda, Gronheit, & Schlegel, 2011). The Parkinsonian voice has been described qualitatively as breathy, rough, hoarse, tremulous, abnormally pitched, having reduced pitch range, and unusually quiet ( Holmes, Oates, Phyland, & Hughes, 2000).įundamental frequency (F0), a result of the rate of vibration of vocal folds, is perceptually related to vocal pitch. Vocal symptoms are also common, with speech deficits occurring in 60–80% of patients ( Canter, 1963 Darley, Aronson, & Brown, 1969 Mutch, Strudwick, Roy, & Downie, 1986). Characteristic symptoms include tremor, rigidity, dyskinesias, and postural gait changes ( Lang & Lozano, 1998). Parkinson’s disease is a neurological disorder characterized by the progressive loss of dopaminergic neurons in specific brain areas and occurs most prevalently in older adults ( Lang & Lozano, 1998). F0 variability changes over the course of reading a paragraph may not be indicative of PD but rather dependent on non-disease factors such as the linguistic characteristics of the text. F0 variability was both significantly reduced in PD relative to controls and significantly increased in patients with PD during use of dopaminergic medications. Female speakers were found to have higher F0 variability than males. No significant effect of group was seen in the change in F0 variability from the beginning to the end of the reading passage. F0 variability was significantly increased in controls relative to both PD groups and PD patients showed significantly higher F0 variability while ON medication relative to OFF. Participants read a single paragraph and estimates of fundamental frequency (F0) variability were determined for the entire reading passage as well as for the first and last sentences of the passage separately. The variability of fundamental frequency (F0) in 32 individuals (23 male) with PD both ON and OFF levodopa medication was compared with 32 age-matched healthy controls (23 male).
In Parkinson’s Disease (PD), qualitative speech changes such as decreased variation in pitch and loudness are common, but quantitative vocal changes are not well documented.
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