# Cross-Laminated Timber Floor: Analysis of the Acoustic Properties and Radiation Efficiency
## 1 Introduction
[PERSON] et al. [33] characterized the vibro-acoustic behavior of a composite structure and presented a comparison between the sound reduction index predictions and measurements in sound transmission suites, according to ISO 10140-2. [PERSON] et al. [34] compared and validated simulated results with measurements of a timber joist floor, then analyzing the importance of the modes of the case study room and the correlation with the behavior of its floor. [PERSON] and [PERSON] [35] performed experimental investigations to identify the modal properties of such a system and to gain understanding of the sound radiation properties under impact excitation, using both experimental modal analysis (EMA) and the integral transform method (ITM). The results highlight the limitations of standard acoustic laboratories and show the importance of using advance measurement methods to acquire reliable data. In addition to the studies mentioned above, there are also numerous works dealing with the vibro-acoustic characterisation of wooden floors, in particular with the impact noise [36; 37; 38; 39; 40]. Nevertheless, some recent studies have shown the need to study this issue in more detail [41; 42]. A recent study [43] has shown, through a Round Robin Test, how the use of software and calculation models, currently available for the study of the characteristics of multilayer systems, are not reliable when wooden structures are used. For this reason, it is of paramount importance not only to know the characteristics of the materials, but also their radiation efficiency. The study of sound radiation, in relation to the characterization of CLT floors, is still partially incomplete. For these reasons, this paper presents: (i) An acoustic investigation of a 200 mm thick CLT floor, conducted in the laboratory, according to ISO 10140 series standards [44; 45; 46; 47; 48], both using sound pressure and vibration excitation. The systematic use of the rubber ball as exciting source is included, in order to investigate every above-presented parameter with this noise source. Indeed, if some research focused on the analysis of the impact noise produced by the rubber ball for concrete floors [41; 42; 49; 50; 51; 52; 53; 54], only few studies focused on timber floors [55; 56; 57; 58]. (ii) A new mass law for CLT elements in CLT. (iii) In addition to the comparison of the three sound sources, a detailed study on experimental approaches and comparison, with the outcomes of two simulation software for the full characterization of the CLT floors, was provided. (iv) A complete analysis of the radiation efficiency by varying the type of source. (v) Some simulation methods were compared with existing models. The novelty of the research consists of studying the acoustic behavior of a CLT floor with three different noise sources and deriving equations that best fit the insulation characteristics of this type of floor. The article is organized as follows. Section 2 summarizes the physical characteristics of the CLT floor, examined the design of the laboratory used for the measurements and the equations used for the measurements and the theoretical analysis. Section 3 shows the results of measurements, relating to airborne and vibrational noise. Section 4 shows a comparison between simulation methods and measurements. Conclusions are drawn in Section 5.