## 3 Results and Discussion
### Braking Phase--Noise
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Tested Indicator** & & & & & \\  & **Train A** & **Train B** & **Train C** & **Train D** & **Train E** \\ \hline Average crest factor CF, longitudinal & 10.2 & 9.0 & 9.5 & 13.1 & 9.7 \\ direction, variable speed & 19.5 & 21.6 & 10.9 & 13.6 & 40.1 \\ \hline RMS & 0.138 & 0.109 & 0.169 & 0.066 & 0.059 \\ \hline VDV & 1.456 & 0.937 & 1.376 & 0.663 & 0.853 \\ \hline \(L_{Aeq}\), acceleration & 66.3 & 62.3 & 63.1 & 58.0 & 63.8 \\ \hline \(L_{pAFmax}\), acceleration & 71.3 & 66.6 & 69.0 & 62.9 & 69.0 \\ \hline \(L_{Aeq}\), constant speed & 72.4 & 67.7 & 69.0 & 65.9 & 71.4 \\ \hline \(L_{Aeq}\), braking & 66.0 & 58.7 & 63.0 & 61.7 & 62.8 \\ \hline \(L_{pAFmax}\), braking & 74.5 & 66.6 & 71.6 & 66.0 & 67.5 \\ \hline \(L_{Aeq}\) on average & 68.2 & 62.9 & 65.0 & 61.8 & 66.0 \\ \hline \(L_{pAFmax}\), on average & 73.8 & 68.3 & 70.8 & 66.3 & 70.3 \\ \hline \(F_{c}\)1 (excluding CF) & 0.03 & 0.16 & 0.04 & 0.24 & 0.18 \\ \hline \(F_{c}\)2 (including CF) & 0.10 & 0.21 & 0.14 & 0.26 & 0.17 \\ \hline \(\psi_{c}\) & 375.5 & 237.1 & 349.5 & 169.4 & 223 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Final evaluation of the results obtained. Only two wagons in each train were tested, with train B being the only one with a steering wagon. The newest train, train E, achieved values comparable to train C in every noise category. Despite considerable design similarities between the A and C series of trains, trains C performed better than trains A. Trains A recorded the highest average values for both vibrations and noise. Noteworthy is the significantly increased CF value for the vertical vibration signal of train E. Considering that this is a new vehicle and the other indicators are at acceptable levels, this may mean that the dynamic systems in the new vehicle, such as suspension systems or braking systems, adapt and undergo specific changes during the initial period of operation. Initial factory settings and calibrations can be refined during subsequent operations. From the acoustics point of view, the condition for admitting any rail vehicle into operation is that the vehicle only meets standards related to external noise emission. Issues related to assessing noise inside rail vehicles, except noise in the workplace, are often ignored [35,36]. The technical specifications for interoperability relating to the \"Rolling  
Figure 5: Relationship between the magnitude of vibration and the mean noise level using the observations from all trains: (**a**) statistically significant relationship for the vibration dose value (\(p\)-value = 0.018, alpha = 0.05, PCC= 0.43) and (**b**) statistically insignificant relationship for weighted RMS acceleration. \begin{table}
\begin{tabular}{c c c c} \hline \multicolumn{4}{c}{**Vibration–Sound**} \\ \hline location & S-2 & S-3 & S-5 \\ \hline V-2 & 0.02 & 0.06 & 0.07 \\ \hline V-3 & 0.02 & 0.06 & 0.07 \\ \hline V-5 & 0.01 & 0.05 & 0.05 \\ \hline \multicolumn{4}{c}{**Vibration–Vibration**} \\ \hline location & V-2 & V-3 & V-5 \\ \hline V-2 & 1.00 & 0.91 & 0.87 \\ \hline V-3 & 0.91 & 1.00 & 0.87 \\ \hline V-5 & 0.87 & 0.87 & 1.00 \\ \hline \multicolumn{4}{c}{**Sound–Sound**} \\ \hline location & S-2 & S-3 & S-5 \\ \hline S-2 & 1.00 & 0.11 & 0.11 \\ \hline S-3 & 0.11 & 1.00 & 0.10 \\ \hline S-5 & 0.11 & 0.10 & 1.00 \\ \hline \end{tabular}
\end{table} 
Table 5: Normalized cross-correlation for sound and vibration signals at three locations across the wagon (3—wagon center; 2, 5—wagon ends; V—vibration, S—sound measurement). Stock--Noise\" subsystem were adopted as a reference point for permissible noise levels in rail vehicles [37]. Some studies suggest even higher values for an acoustically comfortable metro interior space [38].