Frequency and cooccurrence of vocal tract dysfunctions in the speech of a large sample of Parkinson patients.

In this study, the frequency of occurrence of speech and voice symptoms in 200 Parkinson patients was defined by two expert listeners from high-fidelity tape recordings of conversational speech samples and readings of the sentence version of the Fisher-Logemann Test of Articulation Competence. Specific phonemes that were misarticulated were catalogued. Other vocal-tract dysfunctions, including laryngeal disorders, rate disorders, and hypernasality, were also recorded. Cooccurrence of symptoms in each patient was tabulated. Examination of the patterns of cooccurring dysfunctions permitted classifying the 200 patients into five groups: Group 1 (45% of the patients) with laryngeal dysfunction as their only vocal-tract symptom; Group 2 (13.5% of the patients) with laryngeal and back-tongue involvement; Group 3 (17% of the patients) with laryngeal, back-tongue, and tongue-blade dysfunction; Group 4 (5.5% of the patients) with laryngeal dysfunction, back-tongue involvement, tongue-blade dysfunction, and labial misarticulations; and Group 5 (9% of the patients) with laryngeal dysfunction and misarticulations of the back tongue, tongue blade, lips, and tongue tip. Disfluencies and hypernasality did not follow a systematic pattern of cooccurrence with other vocal-tract dysfunctions.