This one's for Sarah (who sees colours in words) and John (who's colour blind)
From BBC Radio 4......
"As many as one in 2000 people has an extraordinary condition in which the five senses intermingle. This major two part series reveals how synaesthesia is changing our understanding of the world of neuroscience."
Link to "Listen again"
See also the BBC webpage for "Derek Tastes of Earwax" where you can read more and take a couple of interactive tests