What Loud Sound Does to the Inner Ear
Loud sound damages hearing by destroying hair cells in the inner ear, and those cells do not grow back. Damage begins at around eighty-five decibels over a working day, and the safe exposure time halves for every three decibels above that. A concert or a power tool reaches that limit in minutes rather than hours.
The permanence is the part that has to land, because the early stages are painless and reversible-seeming. Ringing after a gig fades, hearing appears to return, and the loss accumulates silently in the frequencies used for speech until it shows up decades later as difficulty following a conversation in a noisy room. The material to leave in the source document is individual assessment: audiogram interpretation and any advice about a specific person's hearing belongs with an audiologist.
Seven scenes carry the explanation: one on how sound becomes a signal, one on hair cells and why the damage is permanent, one on the decibel scale and the three-decibel rule, two on where the limit is actually exceeded in ordinary life, one on the early symptoms worth noticing, and one on protection that people will genuinely use.
