The sound of crumpling a sheet of paper made of plastic or nylon is the rustling sound of a plastic bag when a person holds it tightly in the palm of their hand and then uses force to crumple it. The ear-catching squishing sound when the nylon collides with each other, the places where air gets in seem to be compressed and rise and fall within the limits of each other's nylon. The rustling sound of plastic is similar to the sound of paper and books when they are crumpled.