Acoustic and Perceptual Correlates of Vowel Articulation in Parkinson’s Disease With and Without Mild Cognitive Impairment: A Pilot Study

Prosodic and Segmental Correlates of Spontaneous Dutch Speech in Patients with Parkinson's Disease: A Pilot Study

“…Overall, these results are in line with previous studies [7,22]. Dutch spontaneous speech reflected the expected reduced trend in F0 variability for the PD group, confirming the monopitch tendency common for the hypokinetic dysarthria.…”

“…Owing to privacy restrictions it was not possible to check agreement with another annotator. We used similar criteria for annotation as that in [22]. Suitable vowels were selected according the following criteria:…”

“…To determine vowel articulation differences, we calculated four measurements based on [22]: (1) F1 and F2 variability for each speaker, (2) the vowel space area (VSA), (3) the vowel articulation index (VAI), and (4) the F2 ratio of the vowels /i, I/ and /u, u:/. According to Kim et al [18], the F1 and F2 contrasts reflect a speaker's relative stability in achieving vowel targets.…”

“…According to Kim et al [18], the F1 and F2 contrasts reflect a speaker's relative stability in achieving vowel targets. These measurements were computed based on the description in [18,22], but with introduced normalization to allow relative comparison of different vowels. For each speaker the mean normalized standard deviation of each vowel was calculated.…”

“…A common way to capture this phenomenon is with vowel space area (VSA) mesurement calculated from the first two formants of the corner vowels, and with ratios based on formant measurements. While VSA proved to be unreliable to separate pathological from non-pathological speech [19,20], vowel articulation index (VAI) or F2 ratio of the vowels /i/ and /u/ have been demonstrated to be more sensitive to speech impairment and less to interspeaker variability [21,22]. Speakers' relative stability of reaching a vowel target has been shown to account for speech intelligibility and to contribute to differentiating pathological from non-pathological speech [18,22] To the best of our knowlege, acoustic studies on dysarthric Dutch speech are scarce, as are acoustic studies on articulatory performance of PD during spontaneous speech.…”