Noise Estimation for Future Large-Scale Small UAS Operations

This paper provides estimates for ambient noise levels that may be generated by future unmanned air traffic in low-altitude uncontrolled urban airspace. It is motivated by the need to assess the aural impact on communities from such large-scale close proximity unmanned aircraft operations. We simulate unmanned traffic over urban areas and estimate the noise footprint generated over a day. We compute four metrics namely Leq (the long-term Average dB level), Ln (dB level exceeded n% of the time over a location for n = 10, 50, 90), A55 (Area affected by noise above 55dB) and P55 (population affected by noise above 55dB). The effect of increasing traffic density, varying source noise and different operation altitudes on the measured noise levels is also captured. The estimates show that noise levels alone will not be a nuisance especially with an expected altitude of high speed operations above 200ft (~60m). Future work should measure the spectral content of the sound and the auditory impact of specific frequencies.