Real-time rendering of aerodynamic sound using sound textures based on computational fluid dynamics

Abstract

In computer graphics, most research focuses on creating images. However, there has been much recent work on the automatic generation of sound linked to objects in motion and the relative positions of receivers and sound sources. This paper proposes a new method for creating one type of sound called aerodynamic sound. Examples of aerodynamic sound include sound generated by swinging swords or by wind blowing. A major source of aerodynamic sound is vortices generated in fluids such as air. First, we propose a method for creating sound textures for aerodynamic sound by making use of computational fluid dynamics. Next, we propose a method using the sound textures for real-time rendering of aerodynamic sound according to the motion of objects or wind velocity.

Sound Synthesis of Objects Swinging through Air Using Physical Models

“…A physical model of sword sounds was explored in [6]. Here, offline sound textures were generated based on the physical dimensions of the sword.…”

“…The sound textures were generated using computational fluid dynamics software (CFD), solving the Navier-Stokes equations and used Lighthill's acoustic analogy [7] extended by Curle's method [8]. In this model [6], the sword was split into a number of compact sound sources (discussed in Section 3.2), spaced along the length of the sword. As the sword was swept thought the air, each source moved at a different speed; therefore, the sound texture for each source was adjusted accordingly.…”

“…It can be seen that the only model offering real-time operation with instantaneous variability of physical parameter was [1]. Outputs from [4,6] were used within our listening test, Section 5, to represent alternative synthesis methods. A Japanese katana sword was analysed in [9] by means of wind tunnel experiments.…”

“…The inverse Z-transform of G[z] gives the wake output signal, g[n]. The wake gain was calculated by a discrete implementation of Equation (6). A value of Γ = 0.2 was set perceptually based on sounds generated from experiments (Section 5), giving I w .…”

“…It is known from Equation (5) that the gain is proportional to u(t) 6 , and the greatest speed will be at the tip of a sword, a golf club, etc., during a normal swing. The remaining sources were placed at the hilt and midway between the 6th source at the tip and the hilt.…”