If a tree falls in a forest and no one is there to hear it, does it make a sound? If elevator music stops playing and nobody notices, does it matter if it was ever playing at all? Your answer to the latter may depend on your propensity for anxiety: It’s often said that music was first piped into elevators to calm the nerves of early passengers frightened about plummeting to their deaths.

Others say it was simply a way to entertain them. Certainly, this explains the enduring existence of background music in the public sphere. French composer Erik Satie is often credited with having invented the concept: Between 1917 and 1923, he wrote five pieces of what he called “furniture music,” designed to “be a part of the surrounding noises”—heard, but not listened to. What is now ref...