Outdoor and Indoor Acoustic Characterization of Low-Altitude Flying UAS

The rapid growth of the low-altitude economy is constrained by flight safety and noise concerns associated with unmanned aircraft systems (UAS). To address these challenges, The Hong Kong University of Science and Technology (HKUST) proposed a project within the Hong Kong government's “regulatory sandbox” to investigate the noise characteristics of different low-altitude UAS. This study presents comprehensive noise measurement experiments of a typical 7kg-class multi-rotor UAS conducted under diverse flight conditions in both outdoor environments and an anechoic chamber. The measurement systems, test protocols, and data post-processing methods employed to quantify key acoustic parameters, including Sound Pressure Level (SPL) and Sound Exposure Level (SEL), across various relative positions, are illustrated. The results validate the accuracy and reliability of our test methodology, revealing significant variations in noise profiles with flight conditions. These findings provide critical data to support noise certification and regulatory frameworks for low-altitude operations, fostering the sustainable development of the low-altitude economy.