## 4 Discussion  
The highest sound levels were observed at points directly along the road routes, ranging from 57.9 to 71.2 dB, attributed to traffic noise. The recorded sound levels, including those from points 250 m away from the traffic routes, often exceeded 40 dB (35.4-48.6 dB), encompassing both natural and anthropogenic sounds, demonstrating the acoustic impact of the road routes at this distance. At points 500 m from the roads, sound levels primarily ranged from 33.0 to 42.0 dB, with exceptionally high levels measuring between 43.5 and 47.2 dB. Natural sounds dominated at this distance. Although there are no specific regulations on noise threshold values for environmentally protected areas, it can be concluded that the recorded traffic noise levels were high across all study areas. The most significant noise impact was noted in the immediate vicinity and at a distance of 250 m from the traffic routes. The measurement results indicate a clear relationship between the distance from the noise source and sound level; the sound levels at the points closest to the road were the highest, decreasing as the distance increased. However, in test area P1 for measurement profiles B and C and in test area P4 for measurement profile B, higher sound levels were recorded at a distance of 500 m. In all analyzed research areas, the differences in noise levels between points located from 0 m to 250 m from the road ranged from 13.8 dB to 35.6 dB, with further distances from the traffic route showing no similarly significant changes. Similar findings were reported in [30], which stated that traffic noise was significantly reduced at approximately 500 m from the road and was perceived as a relatively monotonous hum. In flat areas, sound propagation was superficial, whereas in hilly regions, sound waves traveled along depressions, reaching greater distances with higher volume. The Pearson correlation coefficients (Table 6) were negative for all measurement profiles on all test surfaces, indicating a strong, negative, and statistically significant relationship between distance and sound intensity. The correlation coefficient values ranged from r = \(-\)0.668 to r = \(-\)0.998, suggesting a strong to very strong negative relationship between the analyzed variables. The physical principles governing sound waves explain this: as distance increases, sound energy dissipates, resulting in decreased intensity recorded by the meter. This phenomenon is rooted in the laws of physics; in open space, sound intensity diminishes with distance from the source according to the inverse-square law, assuming even dissipation of sound energy. The strong negative correlation emphasizes that distance is a key factor in recorded sound intensity, aiding in monitoring environmental noise and assessing how far from the sound source the noise becomes harmless. An essential element of the research was considering the impact of the terrain on sound propagation. Sound propagation in natural environments is a multifaceted phenomenon involving interactions between ground surface, atmospheric conditions, and topographical features. The propagation of acoustic waves in roadside areas is determined by both the energy of the sound source and the properties of the medium. Under open terrain conditions, meteorological factors play a significant role in the propagation of sound energy. Wind speed and direction, temperature gradients, humidity, and atmospheric stratification influence sound propagation, causing refraction, scattering, and variations in sound level and attenuation. The effects vary depending on distance, ground surface cover, and sound frequency. Sound pressure level increases by approximately 0.4, 0.8, and 1.9 dB per 1 m/s increase in wind speed [63]. Studies of road traffic noise propagation in open terrain have shown a clear reduction in excessive attenuation with increasing wind speed at distances of 40 and 140 m from the source [64].