Aerodynamic and Acoustic Characteristics of Nasal Airflow in Parkinson's Disease.

Purpose: Velopharyngeal incompetence may contribute to speech difficulties in Parkinson's disease (PD) but has been minimally studied. This study investigated the acoustic and aerodynamic characteristics of nasal airflow in people with and without PD.

Method: Twenty adults diagnosed with idiopathic PD and 20 age- and sex-matched controls produced consonant-vowel speech stimuli while wearing a nasal airflow mask and oral microphone. Mean nasal airflow was measured during the 25-ms period immediately preceding consonant release ("burst airflow") and over the central 100 ms of each vowel ("vowel airflow"). Vocal intensity (dB SPL) was also measured over the center of each vowel.

Results: The PD group exhibited significantly higher burst airflow than the control group (7.7 vs. 1.9 cc/s), though vowel airflow did not differ significantly between groups. Vocal intensity was positively associated with burst and vowel nasal airflow only in the PD group, despite comparable mean intensity levels between groups. Within the PD group, disease duration and speech-specific motor scores were significantly correlated with burst airflow, and voice-related quality of life was correlated with vowel airflow.

Conclusions: Velopharyngeal dysfunction in PD was more pronounced during rapid motor sequences (stop consonant bursts) than vowel production and showed dynamic motor deterioration under increasing vocal intensities. The intensity-airflow relationship observed in PD suggests compromised velopharyngeal closure during higher vocal demands. Measures of velopharyngeal dysfunction may be useful markers of axial motor symptom severity, which has a large impact on quality of life and prognosis in people with PD.