Database and figures obtained from the doctoral thesis on Sound attenuation of a periodic array of micro-perforated chamber muffler. The data comprises the analyzed results for the following cases: 1 - *ECM Defect Mode: Analysis of defect modes in expansion chambers 2 - CNN MPCM: Results for inverse optimization of micro-perforated expansion chambers using convolutional neural networks 3 - MPCM Graded Diameter: Analysis of micro-perforated expansion chambers with graded outer diameter 4 - MPCM Graded Internal: Analysis of micro-perforated expansion chambers with graded internal micro-perforation diameter 5 - All results uploaded are in MATLAB figure format extension (.fig)MPCM Graded Perforation: Analysis of micro-perforated expansion chambers with graded perforation diameter