Drumspeak for the sound produced by a bass drum or tympani that's been muffled by a sheet or piece of cloth. Also the sound produced when you strike a tympani with a felt mallet in the center of the head; it produces a "dead" sound (tympani are normally struck about 4" from the rim). Also the sound of a pillow striking someone, and the sound of an explosion that doesn't have a sustained rumble, perhaps because is was a smallish explosion inside of a container. Also the sound of an implosion.