## 3 Results
The change in UPDRS IV was estimated with the lowest error equal to 11.3% (MAE = 1.7, range(UPDRS IV \(\Delta\)) = 15) when employing acoustic analysis of the baseline vowel /o/. The change in RBDSQ was estimated with 16.3% error (MAE = 2.0, range(RBDSQ \(\Delta\)) = 13) based on phonatory analysis of vowel /i/. Finally, the lowest error of FOG-Q change estimation is 13.2% (MAE = 2.8, range(FOG-Q \(\Delta\)) = 22). In this case, the acoustic analysis of vowel /u/ outperformed the other ones. \begin{table}
\begin{tabular}{l c c c c c c c c c c} \hline \hline
**Feature** & /a/ & /e/ & /i/ & /o/ & /u/ & /a/ & /e/ & /i/ & /o/ & /u/ \\ \hline \multicolumn{10}{c}{UPDRS III} & \multicolumn{10}{c}{UPDRS IV} \\ \hline PPQ & \(-0.12\) & \(-0.20\) & \(-0.31\) * & \(0.10\) & \(-0.13\) & \(0.09\) & \(0.40\) ** & \(0.25\) & \(0.21\) & \(0.10\) \\ APQ & \(-0.17\) & \(-0.14\) & \(-0.26\) & \(-0.06\) & \(-0.15\) & \(0.06\) & \(0.08\) & \(0.10\) & \(0.06\) & \(0.03\) \\ FLUF & \(-0.27\) & \(-0.30\) * & \(-0.15\) & \(-0.40\) ** & \(-0.25\) & \(0.17\) & \(0.21\) & \(0.28\) & \(0.04\) & \(0.21\) \\ HNR (Q2) & \(-0.04\) & \(0.08\) & \(0.22\) & \(-0.07\) & \(0.09\) & \(-0.02\) & \(-0.03\) & \(-0.14\) & \(-0.14\) & \(-0.17\) \\ HNR (SD) & \(0.12\) & \(-0.18\) & \(-0.25\) & \(-0.05\) & \(0.19\) & \(-0.10\) & \(0.08\) & \(-0.21\) & \(-0.08\) & \(0.13\) \\ F1 (CV) & \(-0.35\) * & \(-0.26\) & \(-0.04\) & \(-0.28\) & \(-0.38\) ** & \(0.05\) & \(-0.04\) & \(-0.07\) & \(-0.02\) & \(-0.11\) \\ F2 (CV) & \(0.13\) & \(-0.34\) * & \(-0.22\) & \(-0.07\) & \(-0.23\) & \(0.39\) ** & \(0.07\) & \(-0.07\) & \(0.28\) & \(0.21\) \\ F3 (CV) & \(0.29\) * & \(-0.19\) & \(0.22\) & \(0.24\) & \(-0.09\) & \(-0.16\) & \(-0.12\) & \(-0.21\) & \(-0.21\) & \(-0.21\) \\ ER (Q2) & \(0.31\) * & \(-0.15\) & \(0.04\) & \(0.26\) & \(-0.13\) & \(-0.11\) & \(-0.07\) & \(-0.16\) & \(-0.27\) & \(-0.29\) * \\ ER (CV) & \(-0.23\) & \(-0.05\) & \(-0.16\) & \(-0.17\) & \(0.05\) & \(-0.08\) & \(-0.33\) * & \(0.12\) & \(-0.04\) & \(0.14\) \\ F0 (CV) & \(-0.32\) * & \(0.18\) & \(0.21\) & \(-0.19\) & \(-0.30\) * & \(-0.15\) & \(0.12\) & \(0.15\) & \(-0.13\) & \(0.15\) \\ GNE (Q2) & \(0.27\) & \(-0.22\) & \(-0.22\) & \(0.20\) & \(0.17\) & \(0.17\) & \(-0.18\) & \(-0.15\) & \(0.11\) & \(-0.27\) \\ GNE (SD) & \(0.16\) & \(0.32\)* & \(0.23\) & \(0.14\) & \(-0.25\) & \(-0.18\) & \(0.10\) & \(-0.07\) & \(-0.25\) & \(-0.05\) \\ TEO (CV) & \(-0.23\) & \(-0.18\) & \(-0.11\) & \(-0.13\) & \(0.23\) & \(0.29\) * & \(-0.13\) & \(0.28\) & \(0.28\) & \(0.30\) * \\ NNE (Q2) & \(-0.25\) & \(0.14\) & \(-0.12\) & \(-0.19\) & \(0.20\) & \(0.10\) & \(0.16\) & \(0.24\) & \(0.30\) * & \(0.31\) * \\ NNE (SD) & \(-0.12\) & \(0.05\) & \(-0.42\)** & \(-0.06\) & \(0.11\) & \(0.29\) * & \(0.15\) & \(0.16\) & \(0.24\) & \(0.16\) \\ \hline \multicolumn{10}{c}{RBDSQ} & \multicolumn{10}{c}{FOG-Q} \\ \hline PPQ & \(-0.23\) & \(-0.19\) & \(-0.16\) & \(-0.17\) & \(-0.37\) * & \(0.15\) & \(-0.17\) & \(-0.18\) & \(0.12\) & \(-0.10\) \\ APQ & \(-0.28\) & \(-0.37\) * & \(-0.38\) ** & \(-0.29\) & \(-0.32\) * & \(0.08\) & \(0.08\) & \(0.06\) & \(0.14\) & \(0.09\) \\ FLUF & \(0.05\) & \(-0.06\) & \(0.06\) & \(0.10\) & \(-0.18\) & \(-0.41\) ** & \(-0.29\) * & \(-0.10\) & \(-0.35\) * & \(-0.40\) ** \\ HNR (Q2) & \(0.29\) * & \(0.35\) * & \(0.31\) * & \(0.36\) * & \(0.41\) ** & \(0.15\) & \(0.11\) & \(0.12\) & \(0.02\) & \(0.04\) \\ HNR (SD) & \(0.23\) & \(0.36\)* & \(0.10\) & \(0.40\) ** & \(0.30\) * & \(-0.06\) & \(0.07\) & \(-0.18\) & \(-0.20\) & \(0.01\) \\ F1 (CV) & \(-0.23\) & \(0.04\) & \(-0.12\) & \(0.06\) & \(-0.16\) & \(-0.29\) & \(-0.04\) & \(-0.42\) ** & \(0.12\) & \(0.13\) \\ F2 (CV) & \(-0.06\) & \(0.08\) & \(0.16\) & \(0.17\) & \(0.06\) & \(-0.27\) & \(-0.08\) & \(-0.20\) & \(-0.09\) & \(-0.37\) * \\ F3 (CV) & \(0.07\) & \(0.15\) & \(-0.25\) & \(-0.40\) **Due to inter-rater variability as well as intra-rater variability [52; 53; 54], consistent scoring of PD using the commonly used clinical rating scales is not an easy task.