When the left ear receives 438 hertz and the right ear receives 442 hertz, the brain takes the average and the listener perceives 440 hertz: A4; the first A above middle C, which exists at the center of a piano’s grand scale. For A4 to be measured at 440 hertz is a standard known as “concert pitch.” This is the standard upon which all of western music theory is based. When the brain compensates for the difference between the two frequencies, the tone perceived by the listener is not a sterile, unchanging A; it is characterized by a rich, swirling motion, a modulation known as “chorus.” We hear this commonly in ‘80s guitar tones – think The Smiths, Siouxsie and the Banshees, or New Order. This chorus operates by its own frequency, producing a binaural beat inside the brain. Said frequency will vary depending on the tones received by each ear. Said frequency, in fact, entrains brain waves accordingly, thus inducing in the listener an altered state of consciousness (ASC). Different states of consciousness (e.g. sleep stages and emotions) can be measured by observing brain wave frequencies, so it is possible to target a desired ASC by creating the appropriate binaural beat.
We have two ears. We have two eyes, two nostrils, two hands, two feet. We have a gift. The ability to experience conflicting sensory input is a gift. It can be a tool. We can use our gift to experience new textures of perception. “Binaural” comes from the Latin word meaning “with both ears.” New combinations of sensory inputs can offer a breath of fresh air, or the Latin “aura.”