LAUSR

Abstract In this paper, the steady-state and transient sound fields inside 3D enclosed spaces were examined theoretically using the modal expansion method. An analytic formula for the Green’s function was derived allowing to predict the interior sound field for both the harmonic and impulse boundary excitations. A theoretical model was tested numerically for a 3D car-like cavity with a sound absorbing material placed on walls. For a harmonic excitation, calculation results revealed high impact of a frequency and a sound damping on a distribution of the steady-state pressure amplitude. They also indicated irregularly located energy vortices in the active intensity vector field. Simulations of a transient sound field were carried out for a boundary excitation producing a sine wave pulse. Temporal changes in this field were studied using the pressure amplitude determined via the discrete Hilbert transform. A large temporal variability of a distribution of this amplitude was noted due to a strong dependence of a transient sound on a position of the observation point. Simulation results also shown that for a small sound damping on cavity walls, there was an intense sound reverberation inside the cavity.