An experimental study of the atmospheric-driven variability of impulse sounds

Propagating impulse sounds are sensitive to the varying near-surface atmosphere. This study reports on an experimental assessment of this sensitivity under well-controlled outdoor conditions. The experiment, conducted over a flat terrain, features 14 synchronous acoustic sensors at ranges up to 450 m from reproducible, transient sources. It scanned over the upwind, crosswind, and downwind propagations, and also documents the temporal and spatial coherences of the acoustic field. Concurrent atmospheric measurements documented the near-surface, essentially wind-driven atmosphere, and included turbulence monitoring. The analysis reveals how the environmental propagation processes combine to form the large variety of recorded signatures. The deterministic versus stochastic variations of the signatures are distinguished, and both are shown to affect the time of arrival (wander) and the shape (spread) of the pulses. The study also discusses the potential impacts of these variations on acoustic sensing of transient signals like gun shots and explosions.