||Resonant Sonic Material (RSM) transmission spectrum has dips and large phase shifts within low frequency. By using Kirchhoff scalar diffraction theorem, it shows possibility of a light weight low frequency sound focus lens, which is made of using RSM. Intensity spectra were generated by the model program which was deduced from Kirchhoff scalar diffraction theorem. Meanwhile, the investigation of new RSM compositions was conducted. A tuned zoneplate with size 0.82m x 0.82m was then fabricated, with rectangular phase step zones. Each has variation within ± 2° with its optimized frequency 460Hz. The open field test was performed. Several intensity spectra were obtained and they showed positive evidence towards sound focusing of the zoneplate.