Loudness and Phase

People do not perceive the loudness (called as volume) of sound in direct proportion to actual power contained in waves. Instead, your ears and brain

Figure-- Sounds from reflected paths (like X, Y, and Z) combine with the direct-path sound (D) to produce what a listener hears.

sense sound levels according to logarithm of actual intensity. Another variable in transmission of sound is phase with which waves arrive at your ears. This allows you to tell from which direction the sound is coming, and it can generate dramatic variations in the perceived sound volume as well.