It has happened to you. Some song wriggles its way into your brain and won't leave. Now imagine that the distant tune in the back of your head suddenly becomes very real. A real song. Real drums. Real guitar. Volume. These are called musical hallucinations and there are some people who actually suffer from them on a daily basis.

We hear first from Leo Rangell who awoke one day to the sound of a rabbi singing. Twelve years later, the music is still there. He talks with reporter Lulu Miller about what he thinks the music is trying to tell him. Then Michael Chorost-- a writer who abruptly went deaf one day--tells us about how a world without sound is filled with music.

We talk to scientists Oliver Sacks, Diana Deutsch, and Tim Griffiths to try to understand WHY our brains would produce such vivid music.