From Dustin Curtis’s discussion with the man who designed Disney World’s sound system:
The system he built can slowly change the style of the music across a distance without the visitor noticing. As a person walks from Tomorrowland to Fantasyland, for example, each of the hundreds of speakers slowly fades in different melodies at different frequencies so that at any point you can stop and enjoy a fully accurate piece of music, but by the time you walk 400 feet, the entire song has changed and no one has noticed.
Think about that for a while: it’s music that few people ever consciously notice, but undoubtedly contributes to the park’s experience. It’d be a very different place without any music. Think about what elements can play a role like that in your own work.
(Via Bryan Rees.)