# Noise Impact Analysis of School Environments Based on the Deployment of IoT Sensor Nodes
## 3 Results
### Comparisons  
As can be deduced from the histograms, the data do not follow a normal distribution. Thus, nonparametric tests were selected for the statistical study: the Kruskal-Wallis H test [PERSON] (1968) for overall comparisons and the Mann-Whitney U test [PERSON] (1968) for two-sample comparisons. The data grouped by hour were used. Specifically, the Kruskal-Wallis H test has resulted that noise intensity differs from building to building (H(4) = 114.365, \(p\) < 0.001). The corresponding Mann-Whitney U test was then executed to compare the noise intensity between buildings B10 and B11, which resulted in a statistically significant difference for the noise between the two buildings, z = 2801.00, \(p\) < 0.001. Similarly, the Mann-Whitney U test was executed to compare the intensity of noise between the B20 and B21 buildings. The outcome produced a statistically significant difference for the noise between the two buildings, z = 2801.00, \(p\) < 0.001. Similarly, the Mann-Whitney U test was executed to compare the intensity of noise between the B20 and B21 buildings. The outcome produced a statistically significant difference for the noise between the two buildings, z = 2801.00, \(p\) < 0.001. Similarly, the Mann-Whitney U test was executed to compare the intensity of noise between the two buildings, z = 2801.00, \(p\) < 0.001. Similarly, the Mann-Whitney U test was executed to compare the intensity of noise between the two buildings, z = 2801.00, \(p\) < 0.001. Similarly, the Mann-Whitney U test was executed to compare the intensity of noise between the B20 and B21 buildings. The outcome produced a statistically significant difference for the noise between the two buildings, z = 2801.00, \(p\) < 0.001. Similarly, the Mann-Whitney U test was executed to compare the intensity of noise between the two buildings, z = 2801.  
significant difference for the noise between the two buildings, z = 2469.00, \(p\) < 0.001. Finally, the Mann-Whitney U test was accomplished to compare the intensity of noise between the B10 and B30 buildings, which again resulted in a statistically significant difference for the noise between the two buildings, z = 2152.00, \(p\) < 0.001. We followed the same approach for the temperature and the humidity values. The H test showed that both temperature and humidity values differentiate among buildings (H(4) = 131.657 and \(p\) < 0.001, H(4) = 77.576 and \(p\) < 0.001, respectively). The U test for temperature comparisons between buildings B10 and B11 revealed a statistically significant difference (z = 9141.00, \(p\) < 0.001). Equivalent results were obtained when we compared the temperature values between buildings B20 and B21 (z = 7143.00, \(p\) < 0.001) and between B10 and B30 (z = 6425.00, \(p\) < 0.001). The U test execution for the relative humidity values led to similar results for buildings B10 and B11: z = 3697.50--\(p\) < 0.001, while it did not output a statistically significant difference for the other building comparisons (B20 and B21: z = 4493.50--\(p\) = 0.862, B10 and B30: z = 3959.00, \(p\) < 0.131). Furthermore, we conducted an analysis to identify the evolvement of the intensity of the noise per hour throughout the school complex. The H test showed (Table 12) that the noise intensity varies during the working day, H(5) = 232.851, \(p\) < 0.001. The 1 st hour is \"quieter\" than the 3 rd (\(p\) = 0.000), the 4 th (\(p\) = 0.000), the 5 th (\(p\) = 0.000), and the 6 th hour (\(p\) = 0.000). Correspondingly, the 2 nd hour is also \"quieter\" than the next ones, and so on. Despite, as already mentioned, the sample being relatively short, the statistical results confirm some empirical conclusions that a trained educational professional would draw. In particular:  
* On the highest floors we have higher temperature and lower humidity;
* High school is noisier than the senior high school;
* The noise intensity evolves during the hours.