Liz Else, associate opinion editor

(Image: Dan Wilton/RedBulletin)

Neil Harbisson can only see shades of grey. So his prosthetic eyepiece, which he calls an eyeborg, interprets the colours for him and translates them into sound. Harbissons art sounds like a kind of inverse synaesthesia. But where synaesthetes experience numbers or letters as colours or even taste words, for example, Harbissons art is down to a precise transposition of colour into sound frequencies. As a result, he is able to create facial portraits purely out of sound, and he can tell you that the colour of Mozarts music is mostly yellow. Liz Else caught up with him at the TEDGlobal conference.

When did you realise you were colour blind? When I was a kid they noticed that I had a big problem with colour blindness. They thought it was the normal red-green type, but it wasn't. Eventually, when I was 11 years old, they diagnosed me with achromatopsia, which means I can only see shades of grey. About one in 33,000 people have this type of colour blindness.

What is the gadget you are wearing? It's a sensor that lets me see colours.

How does it work? Colour is basically hue, saturation, and light. Right now, I can see light in shades of grey, but I cant see its saturation or hue. This gadget detects the lights hue, and converts the light into a sound frequency that I can hear as a note [wavelength is inversely proportional to frequency so it can easily convert the wavelength of the light into a sound frequency]. It also translates the saturation of the colour into volume. So if its a vivid red I will hear it more loudly.

All the translation happens in a chip on the back of my neck - it's all held by pressure onto the bone. It stays there all the time when I go to bed. In September I'm having it osteointegrated - which means that part of the device will be put inside my bone in a hospital in Barcelona and then the sound will resonate much better then. It took a year to convince them that it was ethical and part of me.

How long did it take you to learn how to use it? About five weeks but it was five weeks of 24/7. After five weeks my headaches went away and it became automatic. That was in 2004. Now it feels normal.

What is it like? Your world must look very different. Its like an extra sense, a seventh sense. Its not synaesthesia. Synaesthetes see colour. I never do. I hear it through bone and see beyond the normal.

Can you go beyond the normal range of the 300 or so visible hues? I can do infrared spectrum - I see colour that is invisible, like some of the animals that see at night. And also ultraviolet. The thing about UV is that its good to detect it because it damages the skin and I can detect it. I can build a picture that no one else sees.

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