Contrary to what you may expect, sound is not ‘out there’ in the world but a product of our brains. In fact, sound develops through a recreation of vibration information from the external environment. This poses interesting questions about the nature of perception and reality, and the way we experience the world. The article starts with a discussion about the biological nature of sound and hearing, and then moves to a Philosophy of Sound that challenges the way we think about the world and our role within it.