Antti Kelloniemi

Acoustic Modeling Using the Digital Waveguide Mesh

The digital waveguide mesh has been an active area of music acoustics research for over ten years. Although founded in 1-D digital waveguide modeling, the principles on which it is based are not new to researchers grounded in numerical simulation, FDTD methods, electromagnetic simulation, etc. This article has attempted to provide a considerable review of how the DWM has been applied to acoustic modeling and sound synthesis problems, including new 2-D object synthesis and an overview of recent research activities in articulatory vocal tract modeling, RIR synthesis, and reverberation simulation. The extensive, although not by any means exhaustive, list of references indicates that though the DWM may have parallels in other disciplines, it still offers something new in the field of acoustic simulation and sound synthesis

Simulation of Room Acoustics using 2-D Digital Waveguide Meshes

A novel method for simulation of acoustic spaces, such as concert halls or listening rooms, using several 2-D digital waveguide mesh simulations is discussed. The advantages of this approach include reduced computational load, reduced memory usage, and simplified model structure in comparison to a 3-D waveguide mesh simulation. In approximating the modal frequencies of rooms, all the most important lowest modes get modeled, but some higher modes are missing. The proposed method is useful for finding low-frequency modes and for detecting changes in modal distribution when a sound source is moved, for example. As an acoustic visualization tool, the method is superior over a 3-D simulation in that it can isolate a certain layer of the acoustic wave field and it automatically hides waves that propagate in other directions and thus confuse the visualization

Spatial filter-based absorbing boundary for the 2-D digital waveguide mesh

The digital waveguide mesh is a method for simulating wave propagation, for example, in an acoustic system. Research on the boundary conditions has been going on for years, but adequate solutions for absorbing boundaries have not yet been presented for the digital waveguide mesh. In this work, a new method for constructing absorbing boundaries for a two-dimensional (2-D) rectangular mesh is introduced. With the use of the proposed numerically optimized spatial filtering with an interpolated mesh structure, the reflection was diminished to under -25 dB at incidence angles |/spl theta/|/spl les/79.26/spl deg/ on a frequency band limited only at the very lowest and highest ends.

Boundary conditions in a multi-dimensional digital waveguide mesh

The digital waveguide mesh is a modeling technique suitable for simulation of wave propagation in an acoustic system. Artificial boundary conditions are constructed for the digital waveguide mesh. Absorbing boundary conditions are evaluated and a new method for adjusting the reflection coefficient at values 0/spl les/r/spl les/1 is introduced. The frequency dependent error level of this method is minimized by the use of a second-order FIR filter.

Improved adjustable boundary condition for the 3-D digital waveguide mesh

The digital waveguide (DWG) mesh is a method for simulating wave propagation in multiple dimensions. In three-dimensional form it can be used for modeling room acoustics or resonating bodies of musical instruments, for example. Until now boundary conditions in the three-dimensional DWG mesh have been implemented using methods originating from the updating functions of a one-dimensional digital waveguide. A new boundary structure, which better takes into account the 3-D mesh topology, is now introduced. With this new method, the reflection magnitude is shown to match the desired value over a much wider range of reflection coefficient values than with the earlier method.