Joe Palca at NPR:
Most people can identify a note on a piano, but there will be some people who hear a note, and without even thinking about it, they will know that it was A above middle C — at least if the piano is properly tuned.
Dennis Drayna is a geneticist at the National Institute on Deafness and Other Communication Disorders. He says people with absolute pitch can identify notes on a piano the same way most of us can identify colors.
“And we can always identify red and it’s obvious what’s pink, and we usually don’t confuse the two,” Drayna says. “People with absolute pitch have an analogous ability for their ear.”
To find people with this talent, geneticist Jane Gitschier turned to the Internet. She and her colleagues at the University of California, San Francisco created a Web page where people could test their pitch abilities.
More here.