A method and resulting product produced by attaching a prepared maskant of a desired perforation pattern to cured compound contoured or flat advanced composite materials, directing a narrow stream of highly abrasive grit material of a selected particle size range through a relatively large nozzle under selected high pressure toward the maskant perforations at a very small angle relative to the perforation walls until perforations are formed in the advanced composite material according to the stencil perforation pattern. The perforated sheet produced is particularly adapted for use in sound attenuation structures.