Numerical simulation of the sound of organ pipes

Abstract

Numerical simulations of musical instrument sounds are useful in studies, when questions about the influence of physical parameters stand in first place. Differential equations can be used to solve the given problem. The results given as a discrete sequence can be stored in audiofiles and made audible. In the current project, the influence of the attack of organ pipes with respect to the reverb time of the acoustical environment in the church building is studied by different numerical calculation methods such as finite element method and computational fluid dynamics. The resulting sound pressure and the velocity in a vortex street of the jet emerging from a pipe can be calculated at different listening positions. The computation allows also visualization of the jet in a three dimensional view. In the tests, the same parameters used by organ builders to voice organs are used for the simulation. Main point is the strength of the resulting starting transient and its influence to the acoustical environment. The calculation process which includes the synthesizing and adding a reverb and the results with different voicing parameters will be presented.