Incorporating source directivity in wave-based virtual acoustics: Time-domain models and fitting to measured data

Area of Science:

• Acoustics
• Computational Physics
• Signal Processing

Background:

• Modeling source directivity is crucial for virtual acoustics and auralisation.
• Existing time-domain wave-based simulation methods, like finite difference time domain (FDTD), require accurate source directivity models.

Purpose of the Study:

• To present a novel spatio-temporal model for acoustic wave propagation incorporating source directivity.
• To provide a framework suitable for calibration against measured frequency-dependent directivity patterns.
• To develop a discretisation strategy for efficient implementation on spatial grids.

Main Methods:

• A source term is modeled as a spatial Dirac delta function.
• Differential operators associated with spherical harmonic functions are applied to the source.
• Each spherical harmonic component is driven by time-domain filtering of a source signal.

Main Results:

• The model generates directivity patterns corresponding to spherical harmonics.
• A procedure for deriving time-domain filters for each spherical harmonic channel is demonstrated.
• Numerical results showcase the model's ability to represent source directivity features and compare synthetic with measured patterns.

Conclusions:

• The proposed spatio-temporal model effectively captures source directivity in acoustic simulations.
• The method facilitates calibration with experimental data and offers a convenient framework for numerical discretisation.
• The approach enables locally-defined operations on spatial grids for efficient simulations.