What are the speech characteristics associated with hypokinetic dysarthria as seen in Parkinson’s Disease?
The prominent speech characteristics are reduced vocal loudness and vocal decay, meaning that over time there is a fading in the loudness. This is commonly known as hypophonia. You will also notice hoarseness, harshness, and especially breathiness in the voice, reduced pitch, loudness inflection, the imprecise consonants and distorted vowels that make speech sound very mumbled and slurred. There is also the characteristic of short rushes of speech which is called festinations. There are inappropriate pauses and hesitation when beginning to speak, as well as some dysfluencies and voice tremor, especially when the patient is asked to sustain phonation over time.
However, it should be noted that there is a great deal of variability across people with Parkinson's disease and dysarthria. Some patients can be fairly slow in their speech while others are showing these short rushes of speech and accelerated speaking rates. Some have a very harsh and hoarse voice, and some others are predominantly breathy. There is quite a bit of heterogeneity in the Parkinson’s population.
Antje Mefferd, PhD, CCC-SLP is an Assistant Professor at Vanderbilt University Medical Center. Her research interest is in speech physiology, speech motor control, and the effects of neurological conditions (e.g., neurodegenerative diseases) on speech performance.