## 6 Conclusions  
To study the acoustic radiation characteristics of a track structure formed by multiple SSSFSTs on a bridge, this paper compared and analyzed the acoustic radiation characteristics of different numbers of floating-slabs, investigated the rationality of establishing an acoustic model of the track structure on the bridge, and conducted an in-depth study on the mechanism of the differences. The following conclusions were obtained:  
1. The acoustic radiation characteristics obtained from the acoustic models with different numbers of floating-slabs were significantly different. With an increased number of floating-slabs in the acoustic model, the acoustic radiation capacity of the SSSFSTs and the sound pressure radiated to the outside were enhanced. However, this did not occur in simple linear increments.
2. The vibration characteristics of each floating-slab on the one-span bridge were different, and the acoustic input conditions of different numbers of floating-slabs in the acoustic models used for acoustic analysis led to significant differences in the acoustic analysis results.
3. With the same number of floating-slabs in the acoustic model, there were obvious differences in different floating-slab acoustic contributions at the same sound point. Using acoustic models with different floating-slab numbers, the acoustic contribution of the same floating-slab showed amplified or weakened contributions at the same sound point. Therefore, the number of sound sources in the acoustic model directly affects the acoustic calculation results because the sound waves of each floating-slab can cause acoustic effects during the propagation process.  
For SSSFSTs of a 24 m box girder bridge, this paper studied the influence of acoustic characteristics using different acoustic models of floating-slab numbers. The upper limit number that can be used without leading to an influence of the floating-slabs on the acoustic radiation according to the laying situation of SSSFSTs on the one-span bridge was not analyzed in detail, that is, to what extent an increase in the number of floating-slabs will not influence the acoustic analysis results. This problem requires further analysis in the future. This paper provides a reasonable research basis for the acoustic analysis of SSSFSTs. The field-testing technology of SSSFSTs still needs to be further studied.  
X.Z. ([PERSON]): Establishing the modes and data analysis, writing the original manuscript. X.Z. ([PERSON]): Methodology, review, and revise the manuscript. J.X.: Data processing, review, and editing. L.Y. and G.S.: Data curation, formal analysis, review, and revising the manuscript. All authors have read and agreed to the published version of the manuscript. This research was funded by the National Natural Science Foundation of China, grant number 52362049; the Lanzhou Science and Technology Planning Project, grant number 2022-ZD-131; the University Youth Fund Project of Lanzhou Jiaotong University, grant number 2021014; the Natural Science Foundation of Gansu Province, grant numbers 22 JR5 RA344 and 22 JR11 RA152; and the Young Doctor Foundation Education Department of Gansu Province, grant numbers 2022 QB-063 and 2023 QB-037.  
**Institutional Review Board Statement:** Not applicable.