Mark Batterson describes the amazing ability of the human ear in his book Whisper:

The act of hearing is detecting vibrations of the eardrum caused by sound waves, and the intensity of those waves is measured in decibels. On one end of the sound spectrum is the sperm whale, the loudest animal on earth. The clicking noise it uses to echolocate can hit 200 decibels. Even more impressive, researchers believe that whale songs may travel up to ten thousand miles underwater! Next to the sperm whale is jet engines (150 decibels), air horns (129 decibels), thunderclaps (120 decibels), and jackhammers (100 decibels).

What's on the other end of the sound spectrum?

A whisper, measuring just 15 decibels.

Technically speaking, our absolute threshold of hearing is 0 decibels. That corresponds to a sound wave measuring 0.0000002 pascals, which causes the eardrum to vibrate by just 108 millimeters. That's less than a billionth of the ambient pressure in the air around us and smaller than the diameter of a hydrogen atom!