## 5 Conclusions  
This study constructed mock-up specimens resembling the wet floor structures used in apartments, incorporating SBR latex-mixed mortar to understand the characteristics of floor impact noises. To achieve an effective reduction performance for the floor impact noise, this study mixed SBR latex with different glass transition temperatures and analyzed both the physical properties and the noise characteristics. The results are as follows:  
1. **Mortar strength**: The mixture of Tg 4 \({}^{\circ}\)C SBR latex is effective in enhancing the compressive and tensile strength, while the mixture of Tg \(-16\)\({}^{\circ}\)C SBR latex is effective in reducing the strength. According to the comprehensive analysis of the test values  
Figure 14: Comparison of heavy-weight impact noises for different mixture ratios of SBR latex mortar specimens using impact ball.  
for compressive and tensile strength, along with an evaluation of economic validity, it was determined that the optimal mixture ratio is approximately 7% Tg 4 \({}^{\circ}\)C SBR latex and 5% Tg \(-\)16 \({}^{\circ}\)C SBR latex.
2. **Light-weight impact noise**: Mortar with high strength was more effective in reducing light-weight impact noise. The Tg \(-\)16 \({}^{\circ}\)C SBR latex-mixed mortar showed a reduction effect of about 2-5 dB for light-weight impact noise compared to general mortar
3. **Heavy-weight impact noise**: Mortar with low strength enhanced the reduction effect of heavy-weight impact noise. The Tg \(-\)16 \({}^{\circ}\)C SBR latex-mixed mortar showed a significant reduction effect of about 7-10 dB for heavy-weight impact noise, particularly at the critical 63 Hz frequency band.
4. **Glas transition temperature of SBR latex**: The Tg 4 \({}^{\circ}\)C SBR latex-mixed mortar demonstrated better reduction characteristics by about 2 dB at frequency bands of 125 Hz, 500 Hz, 1000 Hz, and 2000 Hz (except 250 Hz) compared to Tg \(-\)16 \({}^{\circ}\)C SBR latex-mixed mortar. The Tg \(-\)16 \({}^{\circ}\)C SBR latex-mixed mortar exhibited a significantly better reduction performance at the 63 Hz frequency band for heavy-weight impact noise, outperforming Tg 4 \({}^{\circ}\)C by about 10 dB.
5. **Heavy-weight impact sound sources**: The results of heavy-weight impact noise through impact ball excitation showed similar performance across all mock-ups at 125-1000 Hz. The Tg \(-\)16 \({}^{\circ}\)C SBR latex-mixed mortar consistently showed a better reduction performance, by about 7 dB at 63 Hz, in tests with both the impact ball and bang machine excitation methods.  
As a result of these test results, it can be that the Tg \(-\)16 \({}^{\circ}\)C SBR latex, which can more significantly reduce the strength compared to general mortar, is effective for floor impact noises, and in addition to this study, studies to identify the economic optimal mixture ratio while acquiring the effective sound-insulating performance and to focus on the characteristic changes in floor impact noises while applying the dry as well as the wet floor construction method should be conducted.  
Conceptualization, C.-H.H.; methodology, C.-H.H.; software, C.-J.P.; validation, W.-H.L. and C.-H.H.; formal analysis, W.-H.L. and C.-H.H.; investigation, W.-H.L. and C.-J.P.; resources, C.-H.H.; data curation, C.-J.P.; writing--original draft preparation, W.-H.L.; writing--review and editing, C.-H.H.; visualization, C.-H.H.; supervision, C.-H.H.; project administration, C.-H.H.; funding acquisition, C.-H.H. All authors have read and agreed to the published version of the manuscript.  
This work was supported by the Grant No. 112-091-007 from the Core Environmental Technology Development Project for Next Generation of the Korea Ministry of Environment.  
The raw data supporting the conclusions of this article will be made available by the authors on request.  
The authors declare no conflicts of interest.