C. Sound insulation: barrier We are trying to set up a concrete barrier at the roadside, as shown in the image opposite. The following design is proposed: The barrier is made of concrete with a thickness of 10 cm (surface mass of 48 kg/m) The height of the barrier is 3 meters. Appendix A presents beamforming measurements of exterior acoustic sources of an automobile travelling at 59 km/h (based on Yang, 2011). From these measurements, we consider here the automobile as three point sound sources located at a given height, possessing a given frequency, and creating a given pressure level at 1 m from the source. The properties are summarized in the following table: Frquence Niveau Hauteur de la source 190 Hz 84 dB 0,6 m 820 Hz 95 dB 0m 1030 Hz 99 dB 0,1 m The car passes 3 m from the wall, and a house is located 30 m from the intended location of the barrier, as described in the diagram at the end of the statement. We are interested in noise at the level of the door of the house, at a height of 1.5 m. Question: Calculate the insertion loss (IL) of the barrier, assuming that the barrier is infinitely impedance, for each frequency of interest Description of the situation studied: Hauteur de la source: Voir tableau 3 m 3 m 30 m 1,5 m 1.5m Figure 2 Distances in sound barrier design