“Monday’s yellow, Tuesday’s brown, Wednesday’s blue, Thursday’s light brown… If you ask people where lemons are on a piano, they will all put their hands at the top of the keyboard…” That’s Nick Ryan, sound artist and composer – but what on Earth is he talking about? Well, sometimes people get all mixed up. Specifically, their senses are mixed. It’s called synesthesia – a perceptual phenomenon in us humans where we experience one sensory stimulation with or through a secondary sense – letters, numbers or sounds have specific colours to them, words have specific textures, and so on. One in 23 of us understand the world in this way, to varying degrees. In this ultimate episode of the second series of Sound Matters, our unflagging host Tim Hinman straps on his sensorial spelunking kit and goes looking (and listening) for the mystery of synesthesia. Happily, he also travels to Jamaica with Professor Julian Henriques of Goldsmiths College, University of London, and talks sound systems, feeling the bass, and the important difference between mere science and SCIAANCE. Come with us in this last episode of the second series of Sound Matters. Relax and set your senses free. Brought to you by Bang & Olufsen.