The green ‘spiky things’ are stereocilia on the top of inner hair cells of the human ear.
Sound waves through the ear canal and vibrating our bones cause these tiny sensors to react, sending a polarity shift to the neurons colored red below.
If sound is too loud, these stereocilia and tiny hair cells will be damaged.
As time goes on, excess volume will deform enough stereocilia that our hearing will be greatly reduced.
This photo of the sensory cells of the ear by Dr. Sonja Pyott is a winner of an Olympus digital competition. More superb imagery at Science blog’s RetroSpectacle by Shelley Batts.