Ray McAllister sees music: "A bright flash of lavender getting dimmer and dimmer; now we're going over a pink staircase, some lavender violins."
Carol Crane feels music: "I always feel guitars on my ankles and violins on my face."
For Carol Steen, every letter has a color: "Z is the color of beer, a light ale."
And James Wannerton tastes words: "New York is, it's runny eggs. London is mashed potato, but it's extremely lumpy mashed potatoes."
They're not on drugs, they don't have any brain disease. They haven't had a stroke. They're born this way, and they're different from the rest of us, reports correspondent Vicki Mabrey.
Neurologist Richard Cytowic explored this surreal world of synesthesia in his book, "The Man Who Tasted Shapes." He's documented hundreds of cases of synesthesia.
"You know the word anesthesia, which means no sensation," explains Cytowic. "Synesthesia means joined sensation, and some people are born with two or more of their senses hooked together so that my voice, for example, is not just something that they hear, but it's also something that they might see or taste or feel."
He says it's a condition that it's been known to medicine and psychology for 300 years.
"I can remember being in a big school assembly hall - listening to the Lords Prayer recitals," he says, "and it was while listening to that, I used to get flavor after flavor coming in. It was mostly bacon, funnily enough, now I remember."
He didn't know what to think about it. "It wasn't unpleasant. So I just lived with it. It didn't occur to me that it was different," he says.
While most people simply hear a concert, Carol Crane actually feels it - every instrument, every note. She says it's very pleasant, for the most part, "But I notice that every time leave a symphony, I feel as if I've just been run over or something, like I'm just drained."
For New York artist Carol Steen, synesthesia is inspiration. She translates music into art, but she says all sounds produc color for her.
"It's like putting on sunglasses and being able to see the world through the sunglasses," she says.
Though there are dozens of forms of synesthesia, Carol Steen has the most common: seeing letters and numbers in color. The colors never change. She's seen the same letters in the same colors her whole life.
But Carol Crane sees those letters in different colors. Synesthetes may disagree on what color the letter "A" is, but there's one thing they share - a sense of isolation. Many are embarrassed, afraid of being ridiculed, so often they keep their condition to themselves.
"I remember over the years," says Crane, "having discrete experiences with people such as asking them, 'What color is your three or five' or something like that, and I would get a look like 'Are you crazy?' So I stopped asking the question."
About four years ago, she discovered that it was normal and that there was a name for it and that there were other people who had the same experiences. She also discovered that people close to her were keeping the same secret. Her sister, niece and son all have synesthesia; it runs in families.
Although most people have never heard of synesthesia, it is hardly a new discovery. By 1910, scientists had written dozens of papers describing the condition. It was a curiosity, believed to affect creative types - the writer Vladimir Nabokov had it, and so does the painter David Hockney.
Now, medical technology can now reveal what happens inside the synesthete's mind.
Dr. Vilyanur Ramachandran, a neurologist who studies quirks of the brain, was imaging the brain of 27-year-old McAllister, the man who sees music.
During the scan, music stimulated McAllister's audio cortex - and his visual cortex. "That area lit up in him," says Ramachandran. "So you know there was activity in the visual area of his brain even though he was only listening to music."
McAllister describes it as a "Fantasia-"like experience: "Explosions of color all over the place. It looks very beautiful."
This is all the more surprising since McAllister is blind. He lost his sight when he was 12, the result of a degenerative eye disease. But he never lost his synesthesia.
"I may actually be seeing more beautiful colors than most sighted people," he says.
Though scientists can prove synesthesia exists, they still don't know what causes it. Some think it's cross-wiring in the brain; others believe we're all born with synesthesia, but our senses separate as we grow older.
Wannerton says his synesthesia has caused him more than a few problems in his personal life. "I've had girlfriends with names I couldn't stand saying. I'll give you an example. Tracey is a very strong flavored name and it's flaky-pastry. Whenever I was in her company, that's what I thought of constantly."
It sounds amusing, but for Wannerton, synesthesia is a constant battle and at the end of the day, he suffers from sensory oerload.
But still he wouldn't want a cure. "I've had it since I can remember, and taking it away, I wouldn't like the thought of that," he says.
And researchers like Cytowic aren't looking for a cure; they're studying synesthetes for the remarkable clues it offers to the mysteries of the human mind.
"These people experience the world in a different way," he says. "Their senses are wired together differently."
Crane wouldn't have it wired any other way. "I just think the world would be rather flat," she says.