AANTC conducts outdoor noise measurements of an M400 drone across multiple flight conditions

On 28 October 2026, the team led by Professor Xin Zhang at the Aerodynamics, Acoustics and Noise Control Technology Centre (AANTC) of the Hong Kong University of Science and Technology conducted outdoor noise measurements of an M400 drone at the sports ground on HKUST's Clear Water Bay campus. The tests covered different heights and typical flight conditions, together with acoustic recordings of a complete flight profile, providing local field data for studying noise throughout continuous flight.

The measurements form part of a research project on environmental noise in the low-altitude economy supported by Hong Kong's Environment and Conservation Fund (ECF). They continue the team's programme of noise measurements of low-altitude aircraft in mainland China and Hong Kong. The research examines noise sources, sound propagation and operating scenarios to inform environmental noise assessment, technical regulatory recommendations and the development of relevant standards.

A microphone array and complete flight-profile measurements

A ground array of 15 microphones, connected to a multichannel acquisition system, recorded sound simultaneously beneath and on both sides of the flight path. The central and lateral measurement positions provided spatial data for comparing noise at different propagation distances and observation angles, and for studying the distribution of sound at ground level.

Building on previous tests across aircraft types and loading conditions, the campaign extended the range of flight heights, covering hovering at different headings, level flyovers at different heights, and climbs and descents over different vertical ranges. Measurements of a complete flight profile linked hovering, climb, cruise and descent, complementing the individual flight-phase measurements and providing data for studying how each phase contributes to cumulative sound exposure during a flight.

Bringing flight trajectories and wind observations into route noise research

The campaign combined the ground microphone array with real-time kinematic (RTK) positioning equipment and a wind profiler to collect acoustic recordings, flight trajectories and wind observations at different heights. These data will support studies of how aircraft position, operating state and environmental conditions affect noise at ground level, linking the aircraft's acoustic characteristics with its operating environment.

The acoustic, trajectory and meteorological data further enrich the ECF project's local database for low-altitude aircraft. Combining measurements of a complete flight profile with those of individual flight phases will support the evaluation of methods for predicting sound exposure along routes, help refine noise source and propagation models, and provide an experimental basis for environmental noise assessments along routes and around take-off and landing sites.

For standards research, the campaign brings together questions concerning test conditions, environmental factors and sound exposure over a complete flight, providing a local case for the team's ongoing work on environmental noise standards for low-altitude aircraft. These studies will inform the development and refinement of noise measurement procedures, assessment methods and relevant standards, while providing a scientific basis for noise management and technical regulatory recommendations for low-altitude operations in Hong Kong.