Hearing damage from loud sound is cumulative and irreversible. The hair cells in the inner ear that transmit sound do not regenerate. Damage sustained at twenty is still there at sixty, plus everything since.
Why it is not noticed
Because it is gradual and because the brain compensates. Hearing loss in the higher frequencies – the first to go – affects consonants and clarity rather than volume. People notice difficulty following conversation in noise, years after the damage occurred, and attribute it to age.
The exposure
Personal audio devices at high volume for extended periods. The combination matters – loud for a short time and moderate for a long time are both risks, and the daily pattern of hours at high volume is the worst case.
Earbuds that seal the ear canal deliver sound more efficiently, which means the same setting is louder than with open designs.
What protects hearing
Volume limits, which most devices offer and few people enable. The general guidance is around sixty percent of maximum for no more than sixty minutes at a stretch, with breaks.
Noise-cancelling headphones, counterintuitively, because they let you hear at lower volume in noisy environments instead of turning up to compete.
Earplugs at concerts and loud venues. Cheap, effective, and socially unremarkable now in a way they were not.
What does not help
Waiting for symptoms. By the time hearing loss is noticeable, the damage is substantial.
The public health picture
Estimates of young people with measurable hearing loss have risen, and the projections for the coming decades are concerning. This is an entirely preventable problem, and prevention is a setting on a phone.