In 2004, he managed to persuade a surgeon – who remains anonymous – to pierce it into his skull, with the technology becoming part of his body as the bone grew around him.
The sensor captures the frequency of colors and translates them into sounds that it perceives through bone conduction.
Humans normally hear by air conduction with sound waves passing through the outer and middle ears and causing the inner eardrum to vibrate.
But with bone conduction, vibrations are transmitted through the skull or jaw directly to the inner ear.
The color-sound association also means that he perceives colors when listening to music or even speech, with each syllable having a frequency related to the color.
“At first it was all chaotic because the antenna didn’t tell me: blue, yellow, pink, it gave me vibes and I had no idea what color I was in front of me,” Harbisson said.
“But after a while my brain got used to it and it slowly became part of my perception and became normal,” he added.
Although it cannot be turned off, Harbisson’s antenna is silent in the dark. Her “eureka moment” came after dreaming “in color” and realizing that the colors “were created by my brain and not by the chip”.
Although he may be the first person to “hear” the frequencies of color in the form of notes, bone conduction helped Beethoven as he began to go deaf. The German composer realized he could still hear by placing a wooden stick on the piano while biting the other end as he played.
Some 200 years later, bone-anchored hearing aids work the same way through a metal implant inserted into the skull.
In the house where Harbisson grew up and where his mother still lives, a multitude of colorful canvases line the walls, the staircase lined with curious “facial partitions” of celebrities like Di Caprio and Cruise.
These Hollywood stars let Harbisson detect the “sound” of their complexion and the color of their lips, which is rendered by enigmatic charcoal lines.
But Harbisson is now turning his attention to a new project.
He’s created a device in the shape of a big metal necklace, designed to sense the passage of time, and is running a year-long trial to see how it works.
“There is a point of heat which takes 24 hours to go around my neck and which makes it possible to feel the rotation of the planet,” he told AFP.
“Once the brain gets used to it, you can use an app to subtly change the speed of the heat point, which should change your perception of time,” he added.
“You could potentially lengthen the time or make the time appear to go by faster.”
For now, it is a permanent wearable device rather than an implant. A previous incarnation had to be abandoned because he was “getting burned” at 6 pm.
“It’s an art that comes with a kind of risk, but it’s an unknown risk because we don’t have a lot of history of merging bodies and technologies,” he said.