In Grapefruit, Yoko Ono writes the following instructional poem:
OVERTONE PIECE
Make music only with overtones.
1964 Spring
Though most likely intended as conceptual art, I’ve wondered whether it’s possible to create OVERTONE PIECE. When a physical instrument creates a pitched sound, the fundamental tone has to exist in order for the overtones to exist. But with digital technology on our side, could we subtract the fundamental tone from a sound? For example, by using phase inversion or a very sharp EQ cut?
After some unfruitful research and experimentation, I stumbled onto the auditory illusion of the missing fundamental. It turns out that even when the fundamental frequency itself is missing, if the overtones imply a fundamental frequency, then we perceive the fundamental frequency to be there. (!)
Indeed, this auditory illusion is what makes it possible for crappy speakers without a real low end to “produce” low bass sounds: if you leave out the actual low bass fundamental frequencies but leave in the higher overtone frequencies of that same low bass, when you listen to the track, you’ll hear the illusion of a low bass. That’s right: the speaker plays no actual low frequencies, but because we hear the higher overtone frequencies, our brains act like those low frequencies exist. Wild, right?
So, if we try to make music only with overtones, our brain goes ahead and perceives those fundamental tones anyway. Which means that music only with overtones probably wouldn’t sound that novel…more an intellectual experience than a felt one.
But why not venture down the rabbit hole of auditory illusions! My favorites are now the Shepard-Risset glissando (an infinitely descending glissando), the Risset rhythmic effect (an infinitely accelerating breakbeat), and the Deutsch’s scale illusion (where what seem like two series of unconnected notes played to separate ears combine into a single recognizable idea). Shepard tones already flow through the musical culture, from The Beatles’s “I Am the Walrus” to Super Mario 64‘s never-ending stairs to The Dark Knight‘s Batpod motorcycle. Perhaps one of these new favorite auditory illusions shall lead to musical fruit.