At least 75% of patients with Parkinson's disease have disordered speech and voice, with every Parkinson's disease patient developing speech and voice disorders as the disease progresses). Reduced vocal loudness may be one of the first signs of Parkinson's disease and is a classic speech symptom together with monotone, imprecise articulation, hoarse and breathy voice, vocal tremor and short rushes of speech. These characteristics have been associated with rigidity, hypokinesia and tremor in the muscles of the speech mechanism. For example, reduced loudness has been related to rigidity in laryngeal musculature and bowed vocal folds. Decreased range of tongue, lip and jaw movement due to rigidity has been associated with imprecise articulation.
While previous approaches to speech treatment for patients with Parkinson's disease have had limited effectiveness, this chapter will present a new method of intensive voice treatment with well-documented short and long-term efficacy. The rationale, experimental documentation of efficacy, key treatment elements and considerations for implementation of this approach will be discussed.