Engineer Bruce Swedien mixed the song 91 times—unusual for Swedien, who usually mixed a song just once. Instructed by Jones to create a drum sound with "sonic personality" that no one had heard before, Jones constructed a platform for the drum kit with special elements including a flat piece of wood between the snare and hi-hat. He said: "There aren't many pieces of music where you can hear the first three or four notes of the drums, and immediately tell what the piece of music is. But I think that is the case with 'Billie Jean'—and that I attribute to sonic personality."