# Exploring the Influence of Avian Vocal Presence on Appraisal of Urban Soundscapes
## 3 Results
Regarding the second part of the questionnaire, which helped us to rank the sound sources according to their pleasantness, the results obtained are shown in Figure 16.  
To analyze the data attained from the questionnaire in stronger mathematical terms, we examined the statistical significance of the noted differences (shown in Table 6 and Figure 15). To find the statistically significant difference of attribute pairs for different groups, we have used the so-called \(t\)-test and, subsequently, ANOVA (Analysis of the Variance) [47; 48]. Before performing the tests, certain assumptions must be fulfilled (e.g., normality of data, homogeneity of variance, independence, random sampling). The aforementioned calculations are included in Appendix A. \begin{table}
\begin{tabular}{c c c c c} \hline
**Groups** & **Pair Number** & **Avg** & \(\sigma\) & \(\sigma^{2}\) \\ \hline  & 1 & 5.24 & 1.87 & 3.50 \\  & 2 & 3.28 & 1.63 & 2.64 \\  & 3 & 5.14 & 1.61 & 2.60 \\ Children’s Park & 4 & 3.16 & 1.65 & 2.73 \\  & 5 & 5.18 & 1.47 & 2.15 \\  & 6 & 3.82 & 1.55 & 2.39 \\ \hline  & 1 & 5.36 & 1.76 & 3.11 \\  & 2 & 3.60 & 1.59 & 2.52 \\ Children’s Park + Blackbird & 3 & 4.62 & 1.89 & 3.56 \\  & 4 & 3.62 & 1.83 & 3.36 \\  & 5 & 5.54 & 1.64 & 2.69 \\  & 6 & 3.38 & 1.43 & 2.04 \\ \hline  & 1 & 6.02 & 1.01 & 1.02 \\  & 2 & 4.32 & 1.65 & 2.74 \\ Children’s Park + Blackcap & 3 & 5.64 & 1.37 & 1.87 \\  & 4 & 4.22 & 1.58 & 2.49 \\  & 5 & 5.12 & 1.37 & 1.87 \\  & 6 & 3.94 & 1.70 & 2.90 \\ \hline  & 1 & 6.24 & 0.95 & 0.90 \\  & 2 & 4.78 & 1.89 & 3.57 \\ Children’s Park + Chaffinch & 3 & 5.24 & 1.67 & 2.78 \\  & 4 & 4.66 & 1.67 & 2.78 \\  & 5 & 4.96 & 1.73 & 3.00 \\  & 6 & 5.10 & 1.65 & 2.73 \\ \hline  & 1 & 5.04 & 2.30 & 5.28 \\  & 2 & 2.92 & 1.52 & 2.31 \\ Children’s Park + Great Tit & 3 & 4.56 & 2.29 & 5.25 \\  & 4 & 3.36 & 2.01 & 4.03 \\  & 5 & 5.16 & 1.60 & 2.57 \\  & 6 & 3.00 & 1.48 & 2.20 \\ \hline  & 1 & 5.76 & 0.93 & 0.86 \\  & 2 & 4.00 & 2.40 & 5.76 \\ Children’s Park + Robin & 3 & 5.40 & 1.10 & 1.20 \\  & 4 & 4.36 & 1.85 & 3.43 \\  & 5 & 5.00 & 1.08 & 1.16 \\  & 6 & 4.00 & 1.31 & 1.72 \\ \hline \end{tabular}
\end{table} 
Table 6: A detailed analysis of each considered recording (pair number according to Table 1). The experimental research methodology postulates the manipulation of one independent variable, which is, in this case, added birdsong sounds, while other variables are kept constant for both the experimental groups and the control group [47]. In each iteration, the two groups (i.e., one control and one experimental) represent independent samples on which statistical significance can be established. When using a two-sample \(t\)-test for evaluation of the difference between means of small independent samples, it is necessary to specify the level of significance \(\alpha\) and to determine the degrees of freedom (\(N-1\)), where \(N\) is defined as the size of the sample (as is common in similar statistical  
Figure 16: The distribution of participants’ responses (in percentage). Figure 15: Comparison of mean values. analyses we set \(\alpha=0.05\) which corresponds to 95% certainty). The results of the \(t\)-test applied to the listeners' responses on each environment for each attribute pair are shown in Figures 10 and 11. The so-called \(t\)-value, which is the core of the \(t\)-test, is calculated according to the following expression [47]:  
\[t=\frac{\overline{X}_{\text{exp}}-\overline{X}_{\text{cont}}}{\sqrt{\frac{ \sigma_{\text{exp}}^{2}}{N_{\text{exp}}}+\frac{\sigma_{\text{cont}}^{2}}{N_{ \text{cont}}}}} \tag{1}\]  
where \(\overline{X}\), \(\sigma^{2}\), and \(N\) denote mean values of responses, variance, and number of samples, respectively, while indices \"exp\" and \"cont\" refer to the experimental and control groups, respectively.