## 4 Predictions Validation  
The above scenarios and predictions were performed before the construction of this shopping centre, the study being a mandatory requirement to obtain the construction permit. In Figure 16, presented are the satellite images with the analysed area before the construction and the other image with the construction finalized and functional. In this chapter, a validation procedure of the previous predictions is proposed. The validation procedure consists of a comparison of the noise levels obtained through simulation with those measured in the field.  
Figure 14: In—Scenario 5 (**left**: 4 m, **right**: 10 m).  
Figure 15: Ln—facade calculation plots (**left**: Scenarios 1, 2, 3 and 4, **right**: Scenario 5).  
It must be mentioned that the constructor has implemented the noise barrier studied in Scenario 2 and presented in Figure 17.  
The noise maps revealed that the most exposed buildings are situated near the noise sources. As is presented in Figure 1, for each residential building, a virtual receiver was defined according to the location in the measurement campaign, performed before the construction. The validation procedure is based on the comparison of the sound pressure levels predicted with those measured in receiver points 6, 7 and 8. The measurements were made using a FUSION sound level meter from the company 01 dB, mounted on a tripod at a height of 1.5 m. The measurements were performed both in the day and night periods, and in Figure 17, the presented images are from during the measurements and below each image are the overall sound pressure level (OASPL) variation in time and the averaged spectrum for the measured period. The measurements during the day indicate high-amplitude peaks which are produced by the unloading/loading from the supply van.  
Figure 16: Analysed area (**left**: before constructing the shopping centre, **right**: after the construction).  
Figure 17: Noise measurements in R6 point during the day and night periods (**upper part**: images with the sound level meter, **bottom**: average sound spectra and the Laeq (1 s) variation in time, **left part**: day, **right part**: night).  
It must be mentioned that during the night measurements, the cooling systems were functional and the measurements were made in a period with no traffic and no other noise sources, as can be seen from the variation of the Laeq 1 s (where one second denotes the time period over which the fluctuating sound levels were averaged).  
During daytime noise measurements, unloading and loading activities were performed on the supply ramp, as shown in Figure 18.  
In Figure 19, presented are the sound pressure levels in the measurement points R 6, 7 and 8, measured before and after the construction of the shopping centre, and also the sound pressure levels resulting from the acoustic prediction made for Scenario 2. The measurements during the day indicate that the noise trend will increase after the construction of the centre. The values obtained from the acoustic prediction are different from those measured, this being caused by the fact that in the simulations, the road traffic and other noise sources were not modelled. Considering that no noise sources, other than those studied, were measured during the night, it is considered that the measured noise is generated entirely by the sources on the roof. The comparison of the measured data with the predicted ones during the night indicates good agreement between them, and it can be concluded that the prediction results are valid and this numerical solution is a good tool for noise assessment and prevention method. The differences between the simulated and the measured values reach a level of maximum at 1.5 dB.  
Figure 19: Comparative analysis between the predicted and the measured sound levels in the “hot spot” receivers for the day and night periods.  
Figure 18: Supply ramp, acoustic barrier and shopping centre building.