The article recounts psychologist Diana Deutsch and her 1970s discovery of the Octave Illusion, which showed that hearing is an active construction by the brain rather than a direct copy of sound. It highlights a quote from Professor Dan Polley about perception being a brain-built reconstruction. The piece introduces The Sound Barrier, a four-part Unexplainable series exploring phantom sounds, the search for silence, and how astronomers "listen" to space, with episodes released Mondays and Wednesdays starting November 3. It also describes how cochlear implants let the brain relearn sound, illustrated by a man who used Winnie the Pooh to reconnect with Bolero.
How Your Brain Builds the World of Sound: Illusions, Implants and the Quest for Silence
The article recounts psychologist Diana Deutsch and her 1970s discovery of the Octave Illusion, which showed that hearing is an active construction by the brain rather than a direct copy of sound. It highlights a quote from Professor Dan Polley about perception being a brain-built reconstruction. The piece introduces The Sound Barrier, a four-part Unexplainable series exploring phantom sounds, the search for silence, and how astronomers "listen" to space, with episodes released Mondays and Wednesdays starting November 3. It also describes how cochlear implants let the brain relearn sound, illustrated by a man who used Winnie the Pooh to reconnect with Bolero.
02:21, 04.11.2025Science
How the Brain Builds Your World of Sound
In the 1970s, psychologist Diana Deutsch was experimenting with a synthesizer when she experienced something uncanny. "It seemed to me that I’d entered another universe or I’d gone crazy or something…the world had just turned upside down!" she later recalled. What Deutsch had created was an auditory illusion — the Octave Illusion (you can listen to it) — and it revealed a fundamental truth about hearing: the brain doesn’t simply record sound, it interprets it.
Hearing is not a raw, moment-by-moment copy of acoustic input; it is the brain’s best inference about the world. As Professor Dan Polley observes:
"Because the brain doesn’t have direct contact with the physical world, everything that we perceive as consciousness is constructed from the activity of the brain."
That raises a key question: when we listen, are we hearing the outside world itself, the brain’s reconstruction, or a blend of both? The distinction matters for everything from how we experience music to how we treat hearing loss.
Exploring the limits of hearing
In The Sound Barrier, a four-part series from Unexplainable, I investigate the edges of human hearing and how scientists and listeners push beyond them. Episodes visit people who are haunted by persistent phantom sounds, researchers trying to define what true silence is, and astronomers who have developed ways to "listen" to signals from space. New episodes will be released every Monday and Wednesday beginning November 3.
The brain’s editing power also makes technologies like cochlear implants effective: by delivering a new pattern of input, implants let the brain relearn how to make sense of sound. In one segment, Noam interviews a man who lost his hearing and then retrained his brain — using recordings of Winnie the Pooh — to relearn familiar music, eventually rediscovering his favorite piece, Bolero.
Listen and learn: the series reveals how perception, memory and technology combine to create the sounds we experience — and how understanding that process can restore hearing and reshape our sense of the world.