One definition is a sound that is produced by one object striking another. Percussion instruments are musical instruments that produce sound in this manner. There are two types: ones that have a vibrating membrane (i.e., a drum head), and ones in which the whole object vibrates, such as claves, cymbals, mallet percussion instruments, steel pans, and brake drums. Dr. Zero is using a primitive form of drumspeak to describe percussive sounds.