 Much of the score was performed on Elliott's bassoon, and also included harp, clarinet, glockenspiel and bells.The distinctive whistles made by the Clangers, performed on swanee whistles, have become as identifiable as the characters themselves, much imitated by viewers.The series creators have said that the Clangers, living in vacuum, did not communicate by sound, but rather by a type of nuclear magnetic resonance, which was translated to audible whistles for the human audience.