Aerial Surround Sound
Urban Prankster tipped me off to Luke Jerram's very cool work:
The Sky Orchestra is an ongoing research project that explores how one can perceive an artistic experience in sleep space. It is an experimental artwork bringing together performance and music to create visual audio installations within the air and within the mind.
Sky Orchestra are developing music specifically for sleeping people which is delivered out of the sky.
Seven hot air balloons, each with speakers attached, take off at dawn to fly across a city. Each balloon plays a different element of the musical score creating a massive audio landscape.