SinisterMotives

Sound volume increases logarithmically as power increases, at least as perceived by the human ear. It takes a tenfold increase in power to create twice the apparent loudness. Phase cancellation and reinforcement also come into play. If you generate a sound whose frequency matches the resonant frequency of the enclosing space, you get what's known as a standing wave. It has a "booming" quality that makes it sound much louder than other sounds in the same room.