Protect Your Hearing: Loudness × Time Adds Up, and There Is No Undo

What harms hearing is the dose: loudness multiplied by time. In US occupational guidance, every 3 decibels louder halves the time your ears can take, and inner-ear sensory cells that die do not grow back. The dose can be managed; a sudden drop in hearing is a same-day matter.

When to see a doctor

Right away, call an ambulance: hearing loss or ringing with a drooping face, a weak arm, slurred speech or severe spinning dizziness — it can be a stroke; hearing loss or ringing after a head injury (NHS, UK). Call 999 in the UK, 911 in the US, 112 in the EU.

The same day: hearing that suddenly drops in one or both ears, even with no other symptoms and even after a concert or a bang — do not wait for morning. In the UK, NICE asks for assessment by an ear specialist or emergency department within 24 hours; the NHS says urgent GP appointment or 111. US guidance (AAO-HNS, 2019) asks for a hearing test as soon as possible: the doctor looks for the cause and may offer treatment that is started early, though the evidence for its benefit is weaker than one would like (Cochrane, 2022). Also the same day: ringing in time with your pulse, or hearing loss with ear pain or discharge (NHS).

Routinely: hearing that fades gradually, often asking people to repeat themselves, ringing that is constant, worsening or affecting sleep or mood (NHS). Ask your doctor for a hearing test.

What is happening

Temporary overload first, permanent loss later. Loud sound first tires the sensory (hair) cells of the inner ear: sounds turn muffled or ring, and this usually passes within 16 to 48 hours, according to the US National Institute on Deafness (NIDCD) — though some lasting damage can remain. Loud, frequent or long exposure damages cells permanently; high pitches go first, then the clarity of speech (WHO). Humans, unlike birds, do not regrow hair cells (NIDCD).

Hidden damage is a hypothesis in humans. In mice, noise after which hearing tests fully recovered still destroyed the connections between hair cells and the hearing nerve (Kujawa and Liberman, 2009). Whether noise does this in living people is not known; one suspected sign is difficulty following speech in noise (Bramhall et al., 2019). An ordinary hearing test does not see it.

Ringing (tinnitus) after loud sound is a sign of overload and sometimes stays for life (NIDCD, WHO). Sensitivity varies — genes, diabetes and smoking raise the risk — and you cannot know in advance whether you are the vulnerable one (WHO).

Where 85 decibels and 8 hours come from. The US National Institute for Occupational Safety and Health (NIOSH) recommends a limit of 85 dBA averaged over an 8-hour workday. Each extra 3 dB doubles the sound energy, so the allowed time halves: 88 dBA — 4 hours, 91 — 2 hours, 94 — 1 hour, 100 — 15 minutes. Even at 85 dBA over a 40-year working life NIOSH estimates an 8% excess risk of hearing loss: small, not zero. The US legal limit for employers (OSHA) is looser — 90 dBA with a 5 dB step, so 100 dBA is allowed for 2 hours instead of 15 minutes. In the UK, the Control of Noise at Work Regulations 2005 require employers to assess the risk from 80 dB(A) and to provide hearing protection from 85 dB(A).

The same logic off the job. For listening, the WHO benchmark for adults is 80 dB for 40 hours a week, 75 dB for children — a guide to total weekly sound, not a guarantee of safety. By the WHO's reckoning, 15 minutes at 100 dB equals a worker's 8 hours at 85 dB. For scale: you have to raise your voice at around 85 dBA (NIOSH); concerts run at 94–110 dBA (NIDCD); clubs and bars average 104–112 dB (WHO). Below 70 dBA even long exposure is unlikely to harm hearing (NIDCD).

Earplugs. Well-fitted earplugs cut exposure by roughly 5 to 45 dB depending on type (WHO). The rating on the package (NRR in the US) comes from a laboratory; real protection is often much lower and depends mainly on fit, which is why NIOSH now recommends individual fit testing for workers instead of estimating protection from the label (NIOSH, 2025).

What to do

Think in dose: a little louder means a lot less time.
Use the arm's-length test: if you must raise your voice to be understood by someone at arm's length, or your ears hurt or ring, it is too loud (WHO).
Carry foam earplugs to concerts, clubs and matches, and use them with power tools. Roll them thin, pull the ear up and back, insert and hold until they expand (WHO).
Take quiet breaks and stand away from speakers (WHO).
Headphones are the same dose: loud headphones, the 60/60 rule and your phone's sound dose. On the street, keep hearing the traffic: don't walk with both ears blocked.
After a loud night, give your ears quiet. Ringing that fades is a signal to cut the dose; hearing that is clearly reduced counts as sudden hearing loss — same day to a doctor.
Get a hearing test at the first signs: small symptoms deserve attention when they persist, bring questions to your doctor.

When this is not the case

Children have a lower WHO benchmark; keep noisy toys and headphones in check.
Existing hearing loss, tinnitus or hearing aids: the same dose rules apply; ask your audiologist which protection suits you.
Tinnitus with thoughts of harming yourself needs urgent help, not a routine appointment (NICE NG155, UK).
Related: the warning signs your body sends first; another harm that adds up silently is sunburn — sunscreen: what SPF means.

Sources

Checked: 24 September 2026