• Changxi Zheng
• Doug L. James

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Fluid sounds, such as splashing and pouring, are ubiquitous and familiar but we lack physically based algorithms to synthesize them in computer animation or interactive virtual environments. We propose a practical method for automatic procedural synthesis of synchronized harmonic bubble-based sounds from 3D fluid animations. To avoid audio-rate time-stepping of compressible fluids, we acoustically augment existing incompressible fluid solvers with particle-based models for bubble creation, vibration, advection, and radiation. Sound radiation from harmonic fluid vibrations is modeled using a time-varying linear superposition of bubble oscillators. We weight each oscillator by its bubble-to-ear acoustic transfer function, which is modeled as a discrete Green's function of the Helmholtz equation. To solve potentially millions of 3D Helmholtz problems, we propose a fast dual-domain multipole boundary-integral solver, with cost linear in the complexity of the fluid domain's boundary. Enhancements are proposed for robust evaluation, noise elimination, acceleration, and parallelization. Examples of harmonic fluid sounds are provided for water drops, pouring, babbling, and splashing phenomena, often with thousands of acoustic bubbles, and hundreds of thousands of transfer function solves.

• Paper (low-res, 3MB PDF)
• Paper (high-res, 37MB PDF)
• Supplemental Video (H.264 60FPS 133 MB)
• Film for SIGGRAPH 2009 Computer Animation Festival
  • 1920x1080 59.94FPS
  • 1280x720 29.97FPS (67MB)
  • 1024x576 29.97FPS (46MB)
  • 854x480 29.97FPS (34MB)
• NSF Project: Sound Rendering for Physically Based Simulation

Changxi Zheng and Doug L. James, Harmonic Fluids, ACM Transaction on Graphics (SIGGRAPH 2009), 28(3), August 2009.

• Fluid sound radiation solving service ( hfsvcd-0.1beta)

• The National Science Foundation(CAREER-0652597, HCC-0905506)
• Alfred P. Sloan Foundation
• Pixar Animation Studios
• Intel Corporation
• Autodesk Maya

• Cornell Chronicle, Computer graphics researchers simulate the sounds of water and other liquids
• Science Daily, Computer Graphics Researchers Simulate The Sounds Of Water And Other Liquids
• New Scientist, Computer-generated sound effects make a splash
• e! Science News, Splash, babble, sploosh: Computer algorithm simulates the sound of water
• Pressetext (in German), Computergrafiker lassen Wassertropfen klingen
• R&G Magazine, Scientist simulate sounds from scratch

• BBC Radio 4, "The Art of Water Music", Midge Ure (presenter), Tom Rice (producer).