How noise damages the inner ear
Sound is detected in the cochlea by hair cells. The outer hair cells amplify soft sounds; the inner hair cells pass the signal, through synapses, to the hearing nerve (see how hearing works). Very loud sound overdrives this machinery, and with enough exposure the hair cells die. They do not regrow, so their loss causes a permanent sensorineural hearing loss: sounds become both quieter and less clear.
Noise is the second commonest cause of sensorineural hearing loss after age. The harm depends on the dose: how loud, how long, how often.
Temporary and permanent threshold shift
After a loud evening, hearing is often dull for a while. On a hearing test this is a temporary threshold shift: the quietest audible sounds have to be louder than before. It usually recovers within a day or two. A shift still present after about two weeks is likely to be a permanent threshold shift, and little further recovery is expected after a month.
A recovered audiogram used to be taken as proof that no harm had been done; that reassurance is now known to be incomplete (see below). Permanent damage usually builds up over years of exposures loud enough to cause temporary shifts, so each one is a warning.
Ringing after a concert
Tinnitus after loud music, a ringing, hissing or whistling most obvious in a quiet room, means the inner ear has been overstimulated. It usually fades with the dullness, within hours or a day or two. It is common: in the festival trial below, 40% of unprotected participants had new tinnitus after a single afternoon.
The 4 kHz notch
Noise leaves a recognisable signature on the audiogram. Hearing is normal in the low and middle pitches, falls away above about 3 kHz, is worst around 4 kHz, and recovers a little at the highest frequencies tested: the “noise notch”. The resonance of the ear canal, which boosts sound in this region, is one reason. With continued exposure the notch deepens and widens, eventually reaching the pitches that carry consonants. A notch is a pattern, not a diagnosis: other inner-ear losses can look similar, so the history of exposure matters as much as the chart (see interpreting hearing tests).
Hidden hearing loss: what is known
Mouse experiments published in 2009 changed thinking about noise. Exposures that caused only a temporary threshold shift, with hearing thresholds returning fully to normal, still destroyed a large share of the synapses between the inner hair cells and the hearing nerve, and the disconnected nerve fibres later degenerated, while the hair cells survived. This cochlear synaptopathy became known as “hidden hearing loss”, because the audiogram cannot see it. It is predicted to make speech in noisy places harder to follow and possibly to contribute to tinnitus.
In humans, the evidence is unsettled. Synaptopathy can only be confirmed by examining the inner ear after death, and studies in living people using indirect measures have given conflicting results. Noise may harm the ear before the audiogram shows it, but it is not yet possible to diagnose hidden hearing loss in an individual with a routine test, and there is no treatment for it.
Synaptopathy: animal data and human measures
In CBA/CaJ mice, noise producing a moderate but completely reversible threshold elevation caused acute loss of inner-hair-cell afferent terminals and delayed spiral ganglion degeneration, with intact hair cells (Kujawa and Liberman, 2009). Proposed human correlates include ABR wave I amplitude, the middle-ear muscle reflex, envelope-following responses, extended high-frequency thresholds and speech-in-noise scores; their associations with noise history have been inconsistent (Bramhall et al., 2019).
How loud is too loud
Sound level is measured in decibels, usually A-weighted (dBA) to match the ear’s sensitivity. The scale is logarithmic: 3 dB more doubles the sound energy. The US National Institute for Occupational Safety and Health (NIOSH) recommends a limit of 85 dBA averaged over an eight-hour day, with the allowed time halving for every 3 dB above that. By that rule the daily allowance is reached after 4 hours at 88 dBA, 2 hours at 91 dBA, 1 hour at 94 dBA, and only 15 minutes at 100 dBA.
The festival in the trial below averaged 100 dBA for four and a half hours: the day’s allowance was used up in the first quarter of an hour. Many concerts and clubs run at similar levels.
These are workplace limits, meant to protect most people, not everyone. A practical check: if you have to shout to be understood at arm’s length, the level is probably above 85 dB.
Earplugs: the festival trial
Before 2016 the evidence that earplugs protect hearing at concerts was thin: a systematic review by the author’s Utrecht group found a single well-conducted randomised trial. The group then ran its own trial at an outdoor music festival in Amsterdam. Fifty-one adult volunteers with normal hearing were randomly allocated to earplugs or none during a 4½-hour visit, with hearing tests before and after.
- A temporary threshold shift at 3–4 kHz occurred in 8% of protected ears against 42% of unprotected ears.
- New tinnitus occurred in 12% of participants with earplugs and 40% without.
The trial is cited in the WHO Global Standard for Safe Listening Venues and Events (see research). Its limits come from its design: one afternoon, young adults with normal hearing, temporary change measured on the day. It shows that earplugs reduce the immediate effect of loud music; that they also prevent permanent loss over years is a reasonable inference rather than a trial result.
Festival trial: design and secondary outcomes
Single-blind randomised trial, intention-to-treat; 25 participants randomised to earplugs and 26 to none; time-averaged exposure 100 dBA. Temporary threshold shift at 3 and 4 kHz in 4 of 50 protected and 22 of 52 unprotected ears: relative risk 5.3 (95% CI 2.0–14.3) for unprotected ears, number needed to treat 2.9. Mean DPOAE amplitude over 2–8 kHz fell 0.6 dB with earplugs against 2.2 dB without (Ramakers et al., 2016).
Foam plugs or musician’s earplugs
- Foam earplugs are cheap and, rolled thin and inserted deeply, protect strongly. They reduce high pitches more than low ones, so music and voices sound muffled, and a shallow fit protects much less.
- Musician’s earplugs, also called high-fidelity or uniform-attenuation earplugs, contain a filter that reduces all pitches more evenly, so music sounds quieter rather than duller. They are sold ready-made or custom-moulded, with filters of different strengths.
In a study of musicians who tried foam, ready-made and custom musician’s plugs, the protection achieved varied widely between people with every type; custom plugs gave the most even reduction across pitches, and use of all types declined over six months. Fit matters as much as the label, and only an earplug that is worn protects.
When ringing after a concert needs care
Most ringing and dullness fades within a day or two. Some situations should not be left to fade:
- The same day: a sudden, clear drop in hearing, especially one ear that feels blocked, muffled or “dead”, or dizziness with a change in hearing. This is managed as sudden hearing loss, where treatment works better early; do not wait to see whether it passes. Ear pain or bleeding after a bang or blast close to the ear should also be seen the same day.
- Within a few days: muffled hearing or ringing still present after about two days. A hearing test shows whether a threshold shift persists.
- Without urgency: ringing that returns after every exposure, everyday sounds that have become uncomfortably loud, or conversations in noise that have become harder.
Steroids are sometimes given after acute noise injury, by analogy with sudden hearing loss; good evidence that they help is lacking.
Hearing tests for musicians
Professional musicians carry a real risk. In German health-insurance data covering more than 2,000 professional musicians, the risk of a diagnosis of noise-induced hearing loss was about three and a half times that of other insured workers. Sensible checks:
- A baseline audiogram early on, including the frequencies up to 8 kHz where noise damage begins; later tests are compared with your own baseline.
- Repeat tests at regular intervals while exposure continues, and after any ringing or dullness that lasts more than a day or two.
- Otoacoustic emissions, a quick test of outer hair cell function.
- A speech-in-noise test where available, because hearing in noise matters most on stage and the audiogram predicts it poorly.
- A fit check of custom earplugs by an audiologist.
Once damage is done
Permanent noise-induced loss does not recover, and no medicine has been shown to reverse it. What helps is protecting what remains, and, when the loss becomes troublesome, hearing aids and other rehabilitation. Because noise damage blurs sound, extra listening effort in noisy places is often the first real cost. Ear surgery has no role in treating noise-induced hearing loss.
Sources
- Ramakers GGJ, Kraaijenga VJC, Cattani G, van Zanten GA, Grolman W. Effectiveness of earplugs in preventing recreational noise-induced hearing loss: a randomized clinical trial. JAMA Otolaryngol Head Neck Surg. 2016;142(6):551-558. PubMed
- Kraaijenga VJC, Ramakers GGJ, Grolman W. The effect of earplugs in preventing hearing loss from recreational noise exposure: a systematic review. JAMA Otolaryngol Head Neck Surg. 2016;142(4):389-394. PubMed
- Kujawa SG, Liberman MC. Adding insult to injury: cochlear nerve degeneration after “temporary” noise-induced hearing loss. J Neurosci. 2009;29(45):14077-14085. PubMed
- Bramhall N, Beach EF, Epp B, et al. The search for noise-induced cochlear synaptopathy in humans: mission impossible? Hear Res. 2019;377:88-103. PubMed
- Natarajan N, Batts S, Stankovic KM. Noise-induced hearing loss. J Clin Med. 2023;12(6):2347. PubMed
- Van Campen LE, Morata T, Kardous CA, et al. Ototoxic occupational exposures for a stock car racing team: I. Noise surveys. J Occup Environ Hyg. 2005;2(8):383-390. PubMed
- Schink T, Kreutz G, Busch V, et al. Incidence and relative risk of hearing disorders in professional musicians. Occup Environ Med. 2014;71(7):472-476. PubMed
- Crawford K, Willenbring K, Nothwehr F, et al. Evaluation of hearing protection device effectiveness for musicians. Int J Audiol. 2023;62(3):238-244. PubMed
Common questions
Is ringing in the ears after a concert normal?
It is common, but it is not harmless. Ringing, hissing or a dull, blocked feeling after loud music means the inner ear has been overstimulated, and it usually fades within hours or a day or two. In a festival trial, 40% of people without earplugs had new ringing afterwards, against 12% of those wearing them. Each episode is a sign that the sound dose was too high.
How long does ringing after a concert last?
Usually a few hours to a day or two, together with any dullness of hearing. If muffled hearing or ringing is still present after about two days, have a hearing test. A threshold shift that is still there after about two weeks is likely to be permanent. A sudden, clear drop in hearing, especially in one ear, should be seen the same day.
Do earplugs work at concerts?
Yes. In a randomised trial at an outdoor music festival in Amsterdam, a temporary hearing loss at the frequencies most sensitive to noise occurred in 8% of ears protected by earplugs against 42% of unprotected ears, and new tinnitus was also much less common. Earplugs only work when they fit and are worn for the whole time the music is loud.
Will earplugs make music sound muffled?
Foam earplugs reduce high pitches more than low ones, so music can sound dull. Musician's earplugs, also called high-fidelity or uniform-attenuation earplugs, use a filter that reduces all pitches more evenly, so music sounds quieter rather than muffled. They come ready-made or custom-moulded. Whichever type you choose, the fit decides how much protection you actually get.
What is hidden hearing loss?
It is damage to the connections (synapses) between the inner-ear hair cells and the hearing nerve, which a standard hearing test does not detect. It was shown in animals exposed to noise whose audiograms recovered fully. It may explain why some people with normal test results struggle in noisy places, but in humans it cannot yet be diagnosed with a routine test, and the evidence remains conflicting.
This page provides general educational information. It cannot replace an individual assessment, which depends on a full history, examination, audiometry and, where relevant, imaging. If you have sudden hearing loss, severe pain, facial weakness, severe dizziness or discharge with fever, seek medical care promptly.