Research On Sound Propagation Simulation Technology In Outdoor Atmosphere

Sound can greatly improve the user’s immersion and reality in virtual environment.The outdoor scene is indispensable in the virtual environment,but the sound propagation simulation methods in computer graphics are mostly for the indoor scene.Meanwhile,although ray tracing is used for simulation,it cannot accurately simulate some acoustic effects.In acoustics,some wave-based methods are accurate but suffer from low computational efficiency.Considering the inhomogeneity of the atmosphere,an improved FDTD-PE precomputation method is proposed to simulate the sound propagation in outdoor 3D virtual scenes.In the cylindrical coordinate system,the 3D scene is divided into twodimensional planes,and each two-dimensional plane is divided into the near-source region and the far-source region.The FDTD method and the improved PE method are used to calculate the two region sound pressure,respectively.Then,the impulse response of sound pressure data calculated by improved FDTD-PE method is encoded and decomposed into two parts: late reverberation and early reflection.In the late reverberation,the change in a certain reverberation area is selected and stored in the frequency domain.In the early reflection,the peak value and variation trend of each frequency band are extracted and stored.Experiments show that our method can accurately and quickly simulate the sound propagation in the outdoor inhomogeneous atmosphere.Furthermore,an outdoor sound propagation model considering the atmospheric inhomogeneous and ground effect is established.According to the improved FDTD-PE method,a new adaptive FDTD-PE method is proposed to reduce the precomputation time.The adaptive FDTD method computation time length of the near-source region and the adaptive PE method computation area of the far-source region.According to the sound propagation characteristics of the far source region,the method of encoding sound data by function fitting is proposed.Then,according to the encoding method,a decoding and auralization method based on linear interpolation is developed.The experiments demonstrate that our method can simulate the effect of ground on sound propagation quickly and realistically.