The codes presented here concern the exploration of the spatial characteristics of a circular piston, i.e. the acoustic (sound) pressure level at every point in front of the transducer (e.g. a loudspeaker). The acoustic pressure level is calculated by the Rayleigh integral reduced to a Bessel function expression. A 4D plot is given, consisted of frequency response families (at different angles) and polar response families (at different frequencies) for the acoustic far field. The codes provide:
1) 4D plot of the spatial characteristics of a circular piston with slices across the three dimensions;
2) 4D plots of the spatial characteristics of a circular piston with tomography animation across every dimension.
The codes are based on the theory described in:
 I. Iliev, H. Zhivomirov. On the Spatial Characteristics of a Circular Piston. Romanian Journal of Acoustics and Vibration, ISSN: 1584-7284, Vol. XII, No. 1, pp. 29-34, 2015. (http://www.sra.ro/Arhiva/2015/nr1/Paper_5_page29_34.pdf)
A new reference literature has been added.