Has anyone experienced a dream or an LD where your brain improvisationally composes music as the dream goes along? For example, you hit play on a stereo in your dream, and the music starts, but it is a song that you are sure that you've never heard before.

I've had this happen numerous times, and I'm very amazed at how the brain actually creates these songs flawlessly with rhythym and pleasing melodies. In a recent dream my friend, Jared, was showing me a song that he and his band had made, and the song started, and I was immediately flooded with awe and several emotions. It wasn't actually the type of music that my friend and his band actually make, but it was incredible. There was some type of background orchestral music with a playful guitar melody over it. Anyway, once I woke up I could faintly remember the song, and laid there thinking how amazing it was that I'd never heard a song at all like that before, but my mind could create it instantly.

These spontaneous songs happen quite often, and I've wondered why and how. I suppose if the brain can create high-resolution scenery in realtime, than it should be able to do the same with music. It may have to do with the fact that I often whistle or hum, or think of melodies in my mind while I'm doing things at home, to keep my mind occupied. It may be this activity that causes it to show up in dreams, although in a much more instrumental way.

So has anyone else had this happen? Do you usually hear music that you've heard before, or your mind's original music?