Artist Neil Harbisson is completely colour-blind. Here, he explains how a camera attached to his head allows him to hear colour.
Until I was 11, I didn't know I could only see in shades of grey. I thought I could see colours but that I was confusing them.
When I was diagnosed with achromatopsia [a rare vision disorder], it was a bit of a shock but at least we knew what was wrong. Doctors said it was impossible to cure.
When I was 16, I decided to study art. I told my tutor I could only see in black and white, and his first reaction was, "What the hell are you doing here then?" I told him I really wanted to understand what colour was.
I was allowed to do the entire art course in greyscale - only using black and white. I did very figurative art, trying to reproduce what I could see so that people could compare how my vision was to what they saw. I also learnt that through history, there have been many people who have related colour to sound.
At university I went to a cybernetics lecture by Adam Montandon, a student from Plymouth University, and asked if we could create something so I could see colour. He came up with a simple device, made up of a webcam, a computer and a pair of headphones and created software that would translate any colour in front of me into a sound.
It looks like an antenna that comes out from my head and goes up to the front of my face. At the back of my head there's a chip which transforms the light waves into sound, and I hear the colours, not through my ears but through my bone.
At the beginning I had some strong headaches because of the constant input of sound, but after five weeks my brain adapted to it, and I started to relate music and real sound to colour.
I also started dreaming in colour.
It has changed the way I perceive art. Now I have created a completely new world where colour and sound are exactly the same thing. I like doing sound portraits - I get close to someone's face, I take down the sound of the hair, the sounds of the skin, eyes and lips, and then I create a specific chord that relates to the face.
I'm starting a sound portrait gallery of famous faces which began with Prince Charles, who came to Dartington College of Art, where I was studying in 2005.
He asked me, "What's this that you're wearing?", so I asked him if I could listen to his face, and he sounded very harmonic.
Some people might be very beautiful but they might not sound very harmonic, although harmony is subjective.