When you think of sound waves, you probably think of something like this:1But that’s not how sound waves work. A sound wave is more like an earthworm situation:2Like an earthworm, sound moves by compressing and decompressing. Since the low pressure can’t go any lower, that point determines the max amplitude of a sound wave, and the loudest a sound can be, in any given place. The concept of sound is by definition a biological being’s perception of the pressure wave—and if there are no ears around to perceive the pressure wave, there’s no sound. Decibelcar.com: Decibel Equivalent TableMake it Louder: Ultimate Sound Pressure Level Decibel TableNASA: Sound Suppression Test Unleashes a FloodIdiom Zero: How Loud is the Sun?