## 4 Conclusions  
In this work, airborne and impact noise insulation measurements were carried out on a building featuring Cross Laminated Timber floors. In particular, the apparent sound reduction index and the impact sound pressure level measured with a normalized generator and rubber ball impulses were measured step-by-step during the construction phase. In particular, the application of floating floor, suspended ceiling, and the merging of these two technologies applied to the bare Cross Laminated Timber floor was investigated.  
Findings highlighted how this lightweight sustainable timber structures do not present the same performances of heavyweight ones. We can then resume our main conclusions as follows:  
* the bare Cross Laminated Timber floors present similar acoustic performances, thus an average trend can be considered;
* the impact noise reduction offered by suspended ceiling or floating floor excited by a tapping machine is very similar. Regression equations demonstrate that frequencies do not play a significant role; the same consideration is possible even when considering both these techniques at the same time.
* the [PERSON]'s equation does not work with this structure. In particular, for middle-low frequency, [PERSON]'s law fails by a large amount.
* when excited by a rubber ball, a suspended ceiling acts better than the floating floor, especially at low frequencies. The floating floor presents a linear-decreasing trend, which anyway is not able to reduce efficiently the impulse injected by the rubber ball;
* in the case of airborne sound insulation, both floating floor and suspended ceiling offer similar improvements. When merging the two technologies, no significant performance increasing is assessed. In this case, no analytical model was found to correctly predict the final results.  
[PERSON] and [PERSON] developed the research. [PERSON] and [PERSON] defined the methods and comparisons. [PERSON] and [PERSON] studied and analyzed typical wooden structure. [PERSON] and [PERSON] performed acoustic measurements. [PERSON] and [PERSON] collected data and analyses results. [PERSON] and [PERSON] overviewed and supervised the research. [PERSON] and [PERSON] wrote the paper. All authors edited and proofread the paper. All authors have read and agreed to the published version of the manuscript.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Configuration** & \(\text{L}^{\prime}_{\text{n,w}}\) **(dB)** & \(\text{L}^{\prime}_{\text{iA,Fmax,50-630}}\) **(dB)** & \(\text{L}^{\prime}_{\text{iA,Fmax,20-2500}}\) **(dB)** & \(\text{R}^{\prime}\) **(dB)** \\ \hline
1 & 83 & 80 & 80 & 35 \\
2 & 65 & 55 & 56 & 52 \\ \(\Delta_{2}\) & 18 & 25 & 24 & 17 \\
3 & 62 & 59 & 60 & 51 \\ \(\Delta_{3}\) & 21 & 21 & 20 & 16 \\
4 & 52 & 29 & 31 & 53 \\ \(\Delta_{4}\) & 31 & 51 & 49 & 18 \\ \hline \hline \end{tabular}
\end{table}
Table 6: Impact noise and airborne sound insulation weighted index results for each configuration.  
**Funding:** This work was developed within the Interreg Project BIGWOOD, Interreg V-A Italy-Austria 2014-2020 (code ITAT 1081 CUP: I54I1800030006), which is gratefully acknowledged. This work was supported by the Open Access Publishing Fund of the Free University of Bozen-Bolzano.  
**Acknowledgments:** Authors would like to really thank [PERSON] for their precious help in this research and specifically [PERSON].  
**Conflicts of Interest:** The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.