"The Simpsons" annual Halloween special has become a tradition, but according to creator Matt Groening, what makes it special is the music, thanks to the composer collective Bleeding Fingers.

Matt Groening knows what a real theremin sounds like. As a kid who grew up on the celluloid junk food of the 1950s and ’60s, “The Simpsons” creator heard the ghostly wail of that early electronic ...