Times to stabilize sound metrics in rural areas - How long should you monitor?

In areas dominated by the sound from highway traffic, day-to-day sound ambient sound levels can be relatively constant. However, in rural areas, where wind, animals, machinery, airplane overflights, and occasional or distant traffic play larger roles in their contributions to ambient sound. These sources can change day to day, week to week, and season to season. As a result, there is greater variation in sound levels over time in rural areas than in urban areas. This characteristic also affects how long one should collect data with sound level meters to capture a statistically stable sample. In this study, we evaluate the stabilization of sound level metrics LAeq, LA10, LA50, LA90, and LZeq by 1/3 octave band over time for several rural sites. We present recommendations for monitoring times for each metric such that the variation in levels is relatively stable.