# Exploring the Influence of Avian Vocal Presence on Appraisal of Urban Soundscapes
## 4 Discussion  
We analyzed the spectrograms of the obtained recordings from Figures 9-13. When comparing all the spectrograms, it is visible that by adding the sound of birds, a distinct acoustic pattern for each bird species appears in a higher frequency band (i.e., from 1 kHz to 8 kHz). In addition, it is necessary to emphasize that each bird species has a different vocalization pattern, which can also be easily observed in Figures 9-13. By observing the spectrograms, it can be concluded that adding bird sounds complements and enriches the soundscape. However, the question remains how the residents will perceive these newly designed soundscapes, and this is why we investigated the subjective perception and feedback attained from the study participants. Tables 2-5 and Figure 14 show variations in certain objective acoustic parameters, specifically in loudness and sharpness, while other parameters, such as roughness and fluctuation strength, did not change significantly. Loudness and sharpness are indeed a bit higher. Given the high-frequency content of the original bird recordings prior to mixing them with a recording of a children's park, an increase in sharpness was anticipated in the experimental group. Generally, heightened sharpness aligns with an increase in high-frequency content, a range to which human hearing is more sensitive; thus, it is likely that listeners notice the bird sounds more distinctly. The analysis confirmed that adding the sounds of specific bird species to the original signal did not significantly affect roughness or fluctuation strength, as these values were initially low. Given the careful design of the recordings to integrate bird sounds naturally, this outcome aligns well with our expectations. The first part of the questionnaire consists of six adjective pairs with a semantic differential that can describe a certain acoustic environment. When we compared only the mean values of all adjective pairs (shown in Figure 15), more favorable feedback was achieved for the recordings with birds, except in the case of great tit. The second part of the questionnaire is focused on the participants' choices of the most pleasant sound source that appears in each created soundscape. When observing Figure 15, it is apparent that by adding the sound of birds to the existing soundscape recording, the participants' choices of the most pleasant sound source shift in favor of the added singing bird. This is especially visible in cases of the blackcap, chaffinch, and great tit. In the case of blackbird and robin, the distribution is more divided between the sound sources. The reason for this could be the fact that a blackbird and robin \"fitted better\" in  
Figure 18: Calculated F-values (ANOVA calculation where the dashed line corresponds to F-value 2.21, x-axis according to Table 1, where 1 denotes monotonous–diverse; 2 denotes unpleasant–pleasant; 3 denotes artificial–natural; 4 denotes stressful–soothing; 5 denotes inconspicuous–conspicuous; 6 denotes rough–gentle). the original soundscape of the children's park, or in other words, their singing was not that noticeable for most study participants. If we look at the spectrograms, these two birds do have a distinct pattern; however, they are not as intense as the others. In addition, if we observe the results of the conducted \(t\)-test for these two cases, the obtained t-values are not statistically different from the control group (Appendix B), which aligns with the drawn conclusion. Finally, only a few participants decided on the answer, none of the above. It can be concluded that those soundscapes were perceived as very natural and, in general, pleasant for the participants. Regarding the results obtained from statistical methods, namely \(t\)-test and ANOVA, from Figure 17, it can be concluded that the majority of attribute pairs (i.e., 1, 2, 4, 5, and 6) exhibit statistically significant values in two considered environments: children's park with added sound of blackcap and children's park with added sound of chaffinch.