Abstract
In order to incorporate a directive sound source into acoustic simulation using the finite-difference time-domain method (FDTD), this paper proposes an optimization-based method to estimate the initial value which approximates a desired directional pattern after propagation. The proposed method explicitly considers a discretized FDTD scheme and optimizes the initial value directly in the time domain so that every effect of the discretization error of FDTD, including numerical dispersion, is taken into account. It is also able to consider a frequency-wise directivity by integrating the Fourier transform into the optimization procedure, even though the estimated result is defined in the time domain. After the optimization, the obtained result can be utilized in any acoustic simulation based on the same FDTD scheme without modification because the result is represented as the initial value to be propagated and no additional procedure is required.
Highlights
Among the many factors affecting the simulation accuracy including the boundary condition and numerical dispersion, this paper focuses on the directivity of a sound source in finite-difference timedomain method (FDTD)
The same idea has been considered in acoustic simulation to approximate a directive sound source, which utilizes a set of point sound sources distributed around the position of the directive source
Even though the proposed method is explained through a specific scheme in Eqs. (4) and (6) for the sake of easiness, any FDTD scheme can be expressed by the matrix U and vector f1⁄2n, and the proposed method is not restricted to a specific FDTD scheme
Summary
Acoustic simulation has been widely studied for predicting acoustical phenomena. Most methods are classified into the following two categories: geometrical- and wave-based methods. The same idea has been considered in acoustic simulation to approximate a directive sound source, which utilizes a set of point sound sources distributed around the position of the directive source.28,30 It modeled the source in the frequency domain so that the sound field emitted from a point source admits the closed-form expression. Every numerical simulation includes a discretization error, models of the sound source in the conventional methods have not fully taken the effect of discretization into account.30,32 They instead theoretically consider sound propagation and directivity as if there is no numerical error. To the best of our knowledge, except our conference proceeding on the preliminary result, a fully optimization-based representation of a directive sound source, which takes every effect of discretization of FDTD into account, is realized for the first time in the literature.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
