## 5 Conclusions  
This study measured and evaluated the impact sound reduction performances of floor mats used in apartment buildings. The evaluation method we used followed the guidelines outlined in KS F 2865, which specifies a bare slab thickness range of 120 mm to 210 mm. Thus, the impact sound reduction performance of floor mats applied in actual apartment houses was evaluated using various test facilities with different bare slab thicknesses. The standard impact sources included a tapping machine, a bang machine, a rubber ball, and a rubber ball falling from a height of 0.4 m, simulating the impact force generated by children's behavior. The experimental results indicate that the tapping machine, a light-weight impact sound, provided sufficient impact sound reduction performance regardless of the floor mat used and the test room conditions. Furthermore, the impact sound reduction performance increased from the low frequency band to the high frequency band. The bang machine produces heavier impact sounds than other sources, resulting in a lower impact sound reduction performance, even with floor mats installed. In some cases, it may even amplify certain frequency bands. Similar to light-weight impact sounds, the impact sound reduction \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Test Bed with Bare Slab Thickness**} & \multicolumn{8}{c}{**Sample No.**} \\ \cline{2-9}  & **Sample \#1** & **Sample \#2** & **Sample \#3** & **Sample \#4** & **Sample \#5** & **Sample \#6** & **Sample \#7** & **Sample \#8** \\ \hline Test bed A (150 mm) & 4 & 5 & 7 & 10 & 4 & 5 & 6 & 6 \\ \hline Test bed A (180 mm) & 2 & 2 & 7 & 13 & 1 & 1 & 3 & 2 \\ \hline Test bed B (150 mm) & 2 & 2 & 5 & 7 & 2 & 3 & 4 & 4 \\ \hline Test bed C (210 mm) & 1 & 1 & 2 & 2 & 1 & 1 & 1 & 1 \\ \hline Test bed D (150 mm) & 1 & 1 & 2 & 6 & 1 & 2 & 2 & 2 \\ \hline Average & 2 & 2.2 & 4.6 & 7.6 & 1.8 & 2.4 & 3.2 & 3.0 \\ \hline Standard deviation & 1.2 & 1.6 & 2.5 & 4.2 & 1.3 & 1.7 & 1.9 & 2.0 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: The SNQs measured for the floor mat samples using a rubber ball dropping at 1 m height in different test beds. The unit is dB. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Test-Bed with Bare Slab Thickness**} & \multicolumn{8}{c}{**Sample No.**} \\ \cline{2-9}  & **Sample \#1** & **Sample \#2** & **Sample \#3** & **Sample \#4** & **Sample \#5** & **Sample \#6** & **Sample \#7** & **Sample \#8** \\ \hline Test-bed A (150 mm) & 1 & 2 & 2 & 3 & 1 & 1 & 2 & 2 \\ \hline Test-bed A (180 mm) & 1 & 3 & 5 & 5 & 1 & 2 & 4 & 4 \\ \hline Test-bed B (150 mm) & 0 & 1 & 2 & 3 & 0 & 1 & 1 & 1 \\ \hline Test-bed C (210 mm) & 1 & 1 & 2 & 3 & 0 & 0 & 1 & 3 \\ \hline Test-bed D (150 mm) & 0 & 1 & 2 & 3 & 0 & 1 & 0 & 2 \\ \hline Average & 0.6 & 1.6 & 2.6 & 3.4 & 0.4 & 1.0 & 1.6 & 2.4 \\ \hline Standard deviation & 0.5 & 0.9 & 1.3 & 0.9 & 0.5 & 0.7 & 1.5 & 1.1 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: The SNQs measured for the floor mat samples using a bang machine in different test beds. The unit is dB. performance increases from low to high frequency bands. The results of the SNQ analysis indicate that the installation of floor mats may not always reduce impact sound, with a maximum reduction of 5 dB being observed. However, the effectiveness of floor mats varied depending on their type. Rubber balls amplified the impact sound from the 50 Hz band to the 125 Hz band for heavy-weight impacts, depending on the type of floor mat and the thickness of the bare slab. However, the study found that impact sound reduction performance was achieved from the 160 Hz band and above, with a tendency for the impact sound to decrease from the 315 Hz band to the 630 Hz band. The SNQ evaluation showed a minimum of 1 dB and a maximum of 10 dB or more of impact sound reduction performance.