Underwater sound propagation for virtual environments

Realistic sound effect synchronized with visual rendering can greatly improve the immersive sense of a user in virtual reality (VR). Prior work focuses on sound propagation in air without considering the characteristics of underwater, thus cannot be directly extended for underwater scenarios. This paper proposes a novel method for simulating sound propagation in underwater scenes. We combine the normal mode method in oceanography with an improved ray tracing method to effectively calculate underwater sound propagation. A normal mode method is adapted for sound pressure calculation in the low-frequency domain. In the high-frequency domain, by considering the characteristics of underwater, we propose a threshold-based improved ray tracing method to compute the impulse response, bringing results closer to real values at higher efficiency. We sample the possible listener positions and use backward ray tracing to perform interpolation and extrapolation at runtime. Our simulation results are realistic at interactive rendering rates for scenes with moving sources. To the best of our knowledge, this is the first time that a sound propagation model tailored for underwater environment is presented in the field of VR. Various experiments in underwater scenes validated our method.