## 3 Results
### Results of Sound Propagation Modeling  
BS 5228-1:2009 [60] and ISO 9613-2:2024 [62] are among the most commonly used standards for predicting noise levels in open areas. However, they differ in both their methodological assumptions and scope of application. ISO 9613-2 is based on an empirical model that takes into account the propagation of sound from large industrial and linear sources, including losses resulting from atmospheric absorption, screening, terrain type, and meteorological conditions. It is a highly specialized model designed for long-distance noise propagation, most often used in analyses related to industrial or transport infrastructure. At the same time, it requires a large amount of precise input data and is most often implemented in specialized, paid software. Unlike this approach, BS 5228 stands out for its operational flexibility and adaptation to practical field applications, making it extremely useful in environmental analyses conducted in natural conditions--especially where spatial assessment of the impact of individual noise sources is important. Its methodology takes into account key factors affecting sound propagation, such as distance, topography, ground type, and natural terrain obstacles, while limiting the amount of data required. Importantly, BS 5228 can be successfully used in open GIS software such as QGIS (3.34.12 version), which increases the accessibility and usability of this standard in acoustic analyses in forest areas, national parks, and other protected areas. The results of sound propagation modeling from individual research points are presented in Figures 2-5. On the P1 research site (Figure 2), modeling showed a significant impact of terrain on sound wave propagation. The highest traffic noise intensity was recorded in measurement profile A, where the \(L_{\textit{Aeq}}\) sound level reached as high as 70.4 dB. It can be seen that the acoustic impact in this profile covered a much larger area than in profiles B and C. However, its range was clearly limited by the elevation that separates the noise source from the deeper part of the forest--the sound propagated mainly along the road. In profiles B and C, the direct \(L_{\textit{Aeq}}\) measurements were very similar. Noise propagation modeling showed a regular and comparable impact range in these profiles, with slight deviations resulting from local differences in the relatively flat terrain. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Profile**} & **Distance from** & \(L_{\textit{AeqT}}\) & \(L_{\textit{Aeq(mean)}}\) & **Height** & **Dominant** \\  & **Road (m)** & **(dB)** & **(dB)** & **a.s.l. (m)** & **Sounds** \\ \hline A & 5 & 64.1 & & 249.3 & \\ B & 5 & 66.5 & 66.8 \(\pm\) 2.3 & 252.1 & Anthropogenic \\ C & 5 & 68.6 & & 252.0 & \\ \hline A & 250 & 37.1 & & 269.5 & \\ B & 250 & 38.3 & 38.3 \(\pm\) 1.2 & 293.1 & Natural and \\ C & 250 & 39.4 & & 255.2 & anthropogenic \\ \hline A & 500 & 30.3 & & 273.7 & \\ B & 500 & 47.2 & 42.7 \(\pm\) 9.1 & 299.3 & Natural \\ C & 500 & 33.0 & & 259.3 & \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Results of equivalent sound level measurements in research area P4. In study area P2 (Figure 3), measurement profile A is located on flat terrain. The noise propagation modeling revealed a very regular pattern of sound dispersion, with a relatively limited range of influence. The measured \(L_{Aeq}\) sound level at the roadside measurement point was 57.9 dB. The regularity of propagation and the limited range are due to the absence of terrain-induced interference and the strong attenuation of acoustic waves by the ground surface, which is related to the specific characteristics of the local soil conditions. In profiles B and C, higher \(L_{Aeq}\) values were recorded, resulting in a greater extent of noise impact. The terrain in these profiles is more varied--the model shows small depressions caused by local undulations.