Interactive Acoustic Simulation in Urban and Complex Environments

Report developed under Topic A11a-T006, contract W911NF-13-C-0037. Outdoor acoustics simulation plays a vital role in several military and commercial applications. State-of-the-art outdoor acoustics prediction methods are restricted, slow, or limited to simple environments. Specifically, no existing method can simultaneously model atmospheric acoustical phenomena, surface interactions due to complex objects, along with dynamic sound sources and listeners. We developed a multi-domain simulation approach that combines efficient non-linear ray tracing with accurate wave solver to model long-range atmospheric effects as well as scattering due to complex objects. Accurate but computationally expensive wave solver models scattering effects near complex objects, while efficient non-linear ray tracer handles far-field interactions. The results from these solvers are combined using a novel two-way coupling based on equivalent source representation. Our technique is compute and memory efficient, requiring at least 100 times less memory and compute time than prior approaches. We validated our technique by comparing simulation results against analytical solutions and measurement data for outdoor scenes. The resulting acoustic simulation system can be used by the Army and DoD for battlefield planning, training, and simulation systems. It can also be used by federal agencies, acoustical consultants, and architects for urban noise modeling and reduction.