The Sound of a Lightsaber Was Made from a TV Set and a Projector

The iconic hum and swoosh of the lightsaber from Star Wars has a surprisingly analog and accidental origin. Legendary sound designer Ben Burtt was inspired by concept paintings of the laser swords and imagined the sound they would make. For the idle hum, he recorded the sound of an old simplex film projector's interlock motor as it sat idle. This provided the weapon with a steady, almost life-like quality. The second key ingredient was discovered by chance when Burtt walked past a television set with a microphone and picked up the buzz from the cathode ray tube's transmission signal. This interference, a byproduct of the now-vintage television technology that uses electron beams to create images on a phosphorescent screen, provided the perfect crackling energy to layer with the projector's hum.

To create the signature "whoosh" of the lightsaber in motion, Burtt employed a clever and effective technique rooted in a scientific principle known as the Doppler effect. He played the combined hum and buzz through a speaker and then recorded it with another microphone that he waved through the air. This movement created a change in the sound's perceived frequency; as the microphone moved toward the speaker, the pitch would increase, and as it moved away, the pitch would decrease. This simulation of the Doppler effect is what gives the lightsaber its dynamic and believable sense of movement as it is swung. The clashing sounds were created by striking metal rods together and sometimes by the sound of metal on dry ice.