Voice and Speech Characteristics in Patients With Parkinson's Disease

Parkinson's disease (PD) is a progressive neurological disorder frequently associated with hypokinetic dysarthria, characterized by impairments in voice, articulation, and prosody.

This study investigated speech and voice characteristics in Bosnian-speaking individuals with PD using objective acoustic and temporal measures derived from the speech signal.

Participants with PD and age- and gender-matched healthy controls completed sustained vowel phonation, prolonged fricatives (/s/ and /z/), and diadochokinetic (DDK) syllable repetition tasks. All variables were obtained through acoustic analysis, including standard voice parameters, maximum phonation time, sustained /s/ and /z/ durations, the S/Z ratio, and speech timing measures derived from syllable durations, occlusion duration, and voice onset time (VOT).

After correction for multiple comparisons using the false discovery rate (FDR), the most robust group differences were observed for speech timing measures, with participants with PD exhibiting significantly prolonged durations of DDK syllables as well as increased occlusion and VOTs, indicating slower speech timing. Maximum phonation time was also significantly reduced in the PD group. Differences in individual acoustic voice parameters were observed at the uncorrected level but did not remain significant after FDR correction, reflecting substantial interindividual variability.

The findings indicate that, in Bosnian-speaking individuals with PD, temporal aspects of speech production and sustained phonation duration provide the most sensitive acoustic markers of hypokinetic dysarthria. Within the phonological structure of Bosnian, characterized by a compact vowel system and unaspirated voiceless plosives, acoustic speech timing measures appear particularly informative for capturing PD-related speech impairment. These results support the use of acoustic and temporal assessment methods for clinically feasible evaluation of speech disorders in PD and contribute data from an underrepresented linguistic population.