An explicit time-domain finite-element method for room acoustics simulation

The time-domain finite-element method (TD–FEM) is a reliable numerical method for room acoustics simulation. With the recent progress in computer technology, the use of FEM at high frequencies has become a realistic option. However, efficient simulation at high frequencies is still cited as a challenging task. One of the key to realize such simulation is to reduce the discretization error called dispersion error. In this paper, the applicability of an explicit TD–FEM with a dispersion reduction technique called modified integration rule on room acoustics simulation at high frequencies is tested. First, an explicit scheme with frequency-independent impedance boundary condition is derived for addressing boundaries with finite impedance. Then, the accuracy and efficiency of the explicit TD–FEM is demonstrated in comparison with an implicit TD–FEM for sound field analysis inside a cubic cavity with rigid boundaries at the frequencies up to 8 kHz. Finally, the accuracy of the explicit TD–FEM is examined for sound field analyses with finite impedance boundaries. Results showed that the explicit method offered the same accurate results as the implicit method with less computational time, whereas the implicit method was more efficient in term of memory requirement.