## 3 Results and Discussion
### Weighted Indexes Results  
Even if weighted indexes do not provide frequency information, thus eliminating some of the interesting results, it is evident how it is easier to compare measurements using just the single index instead of 18 different values (1/3 octave bands). For this reason, results in terms of weighted index are reported in Table 6.  
It is possible to notice that, for impact noise reduction using the tapping machine, the significant variation is caused by the use of whether a suspend ceiling or a floating floor is similar. Anyway, when applying the second configuration, it is possible to notice that the reduction is different if measured with the rubber ball or with the tapping machine. According to the standard, \(\mathrm{L^{\prime}}_{\mathrm{iA,Fmax,50-630}}\) is the parameter representing the subjective evaluation of the noise disturbance produced by floor impact sound. Conversely, according to literature [20], \(\mathrm{L^{\prime}}_{\mathrm{iA,Fmax,20-2500}}\) is more accurate. In this case, we can see no significant difference comparing the two parameters.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & \multicolumn{6}{c}{**Configuration and Difference (dB)**} \\ \hline
**Frequency [Hz]** & **1** & \(\Delta_{1}\) & **2** & \(\Delta_{2}\) & **3** & \(\Delta_{3}\) & **4** & \(\Delta_{4}\) \\ \hline
100 & 31.9 & \(-\)4.3 & 33.2 & \(-\)1.2 & 38.4 & \(-\)7.2 & 38.8 & \(-\)3.0 \\
125 & 33.8 & \(-\)6.6 & 35.2 & 1.2 & 40.3 & \(-\)2.2 & 40.8 & 4.1 \\
160 & 36.0 & \(-\)6.8 & 37.3 & \(-\)1.1 & 42.5 & 2.3 & 42.9 & 3.2 \\
200 & 37.9 & \(-\)11.4 & 39.2 & 0.5 & 44.4 & \(-\)4.3 & 44.8 & 2.8 \\
250 & 39.8 & \(-\)13.0 & 41.2 & 2.8 & 46.3 & \(-\)2.2 & 46.8 & 2.5 \\
315 & 41.9 & \(-\)14.6 & 43.2 & 3.7 & 48.3 & \(-\)1.6 & 48.8 & 0.6 \\
400 & 43.9 & \(-\)16.5 & 45.3 & 3.5 & 50.4 & \(-\)2.3 & 50.9 & \(-\)0.5 \\
500 & 45.9 & \(-\)15.3 & 47.2 & 1.7 & 52.4 & \(-\)4.6 & 52.8 & \(-\)2.4 \\
630 & 47.9 & \(-\)14.7 & 49.2 & 0.0 & 54.4 & \(-\)5.8 & 54.8 & \(-\)4.8 \\
800 & 49.9 & \(-\)16.4 & 51.3 & 2.2 & 56.4 & \(-\)6.9 & 56.9 & \(-\)5.8 \\
1000 & 51.9 & \(-\)16.5 & 53.2 & \(-\)2.1 & 58.4 & \(-\)8.2 & 58.8 & \(-\)6.8 \\
1250 & 53.8 & \(-\)14.3 & 55.2 & 0.0 & 60.3 & \(-\)9.2 & 60.8 & \(-\)8.0 \\
1600 & 56.0 & \(-\)14.0 & 57.3 & \(-\)3.8 & 62.5 & \(-\)8.8 & 62.9 & \(-\)9.5 \\
2000 & 57.9 & \(-\)13.7 & 59.2 & \(-\)3.0 & 64.4 & \(-\)8.2 & 64.8 & \(-\)9.6 \\
2500 & 59.8 & \(-\)15.2 & 61.2 & \(-\)6.5 & 66.3 & \(-\)10.3 & 66.8 & \(-\)11.1 \\
3150 & 61.9 & \(-\)17.9 & 63.2 & \(-\)8.1 & 68.3 & \(-\)10.3 & 68.8 & \(-\)12.5 \\
4000 & 63.9 & \(-\)18.9 & 65.3 & \(-\)8.4 & 70.4 & \(-\)11.4 & 70.9 & \(-\)13.8 \\
5000 & 65.9 & \(-\)19.8 & 67.2 & \(-\)9.8 & 72.4 & \(-\)12.4 & 72.8 & \(-\)15.0 \\ \hline \hline \end{tabular}
\end{table}
Table 5: Calculated sound insulation values, using [PERSON]’s theory. \(\Delta_{\mathrm{n}}\) represents the difference between the measured and calculated results.  
Considering configuration 3, we can see that almost the same impact reduction is measured with both tapping machine and rubber ball and that no significant difference is found between \(\text{L}^{\prime}_{\text{iA,Fmax,50-630}}\) and \(\text{L}^{\prime}_{\text{iA,Fmax,20-2500}}\).  
Moving to configuration 4, a significant difference can be reported between tapping machine and rubber ball test, evidencing how, for the latter, a significant improvement in performance is assessed in comparison with the bare floor.  
From the sound insulation point of view, when adding a technology of impact noise reduction, we can see a substantial increment of the performances. Anyway, (i) changing the configurations or (ii) merging them do not vary importantly final results.  
Another overall finding is that configuration 3 (floating floor) and 4, where the combination of the two technologies ensures a more insulated partition, are capable to respect the law requirements of most European countries [39].