Customization of the angular spectrum method for calculating the acoustic piston field transmitted through a solid plate using MATLAB

The angular spectrum (AS) model is customized to calculate the spatial acoustic pressure field generated by a piston source and transmitted through a steel plate immersed in water, for normal beam incidence. A MATLAB program is developed for this specific problem combining use of Gauss quadrature and a generalized Filon method. The program calculates the pressure wave number spectrum generated by the piston source and transforms the wave number spectrum into the spatial domain. Convergence analysis show that the MATLAB program is far more efficient than the more traditional approach of using the fast Fourier transform algorithm to transform the pressure wavenumber spectrum into the spatial domain. The MATLAB program is published here and free for others to use. The methods and MATLAB algorithms are obtained by: • Converting the original 2D AS model to a 1D model using cylindrical coordinates. • Combining use of Gauss quadrature and a generalized Filon method for more accurate pressure calculations compared with use of the fast Fourier transform. • Introducing adaptive numerical integration algorithms in MATLAB and error control parameters which are easy to use.