## 4 Conclusions  
This paper describes a study which focused on the human annoyance perception of three short signals with respect to three acoustic parameters: amplitude, duration and amplitude growth rate. Short irritable signals (children's screams, a car passing by and the sound of a grinder) were used in this study. The aforementioned signals were inserted in the most calming and pleasant sound environment, i.e., a stream. The main idea was to get more information from the listeners on what annoyed them the most on already proven distracting short signals with the final goal of improving the quality of life, human well-being and health in urban areas and reducing noise pollution. The study was carried out in laboratory conditions and the listeners had to listen to the recording on the computer with the AKG-55 closed headphones. For this purpose, an interface was specially designed in Matlab which allowed the study participants to adjust the acoustic parameters e.g., the amplitude, duration \begin{table}
\begin{tabular}{c c c c c} \hline \(f_{o}\) & \(f_{t}\) & \((f_{o}-f_{t})\) & \((f_{o}-f_{t})^{2}\) & \((f_{o}-f_{t})^{2}/f_{t}\) \\ \hline
0.47 & 0.40 & 0.07 & 0.0049 & 0.0104 \\
1.00 & 1.20 & \(-0.20\) & 0.0400 & 0.0333 \\
0.57 & 0.70 & \(-0.13\) & 0.0169 & 0.0241 \\  & & & & \(\chi^{2}=0.0678\) \\ \hline \end{tabular}
\end{table} 
Table 2: \(\chi^{2}\)-test results. and the amplitude growth rate of the short signals, while in the background the sound environment stream was played. The amplitude level of the sound environment stream could not be changed. If we observed the obtained results for three irritable short signals, it can be concluded that the \"most important\" parameters, regarding the human annoyance with a particular sound, are its amplitude and duration. To be more precise, the study showed that the sound will become annoying if its sound pressure level was at least 34.30 dB with respect to the level of the background of the stream acoustic environment and if the sound was no shorter than one second. In order to apply the conclusions that were made for this sample to the whole population, the chi-square test was carried out for the obtained results. The \(\chi^{2}\)-test proved our null hypothesis, thus it can finally be concluded that the most common reason for listeners' annoyance is the sound amplitude which is followed by its duration and the amplitude growth rate, respectively. We noted that some bias in this particular study may be present since this research was carried out in laboratory conditions, however we believe that the results of this research can serve as a basis for the further improvement of acoustic environments and making new architectural and urban planning solutions that give rise to overall acoustic comfort. Urban planners, architects, doctors, psychologists as well as acoustic engineers need to work together and benefit from each other's work with a common cause to improve the overall quality of life. By collaborating, we could reduce noise pollution and moreover improve the human health and well-being of residents, especially the ones living and working in urban areas. Future work will be oriented towards expanding the existing calculation for the total distraction coefficient, considering the findings obtained through this study. Another parameter focused primarily on particular sound sources, which are described by their amplitude, duration and the amplitude growth rate, will be introduced into the formula. This should enable us to provide a large database of sound sources ranked according the human annoyance and link the objective and subjective parameters i.e., establish how certain clusters of sound sources influence the overall human perspective of a sound environment. Conceptualization, M.S. and I.D. ; methodology, M.S. ; software, I.D. ; validation, S.G. and A.P. ; formal analysis, M.S. ; investigation, M.S. ; resources, I.D. ; data curation, S.G.; writing--original draft preparation, M.S. ; writing--review and editing, S.G. and A.P.