Noise-induced hearing loss: limits, protection and testing

How loud is too loud

The short version: 85 dBA is the line. NIDCD says sounds at or below 70 dBA are unlikely to cause hearing loss, even after long exposure. Long or repeated exposure at or above 85 dBA can cause it, and the louder the sound, the less time it takes ^[1].

No sound meter? NIOSH's rule of thumb: if you have to raise your voice to talk to someone an arm's length away, the noise is probably hazardous ^[8].

The damage happens in the inner ear. Loud sound damages, and eventually kills, the tiny hair cells that turn vibration into nerve signals. Human hair cells don't grow back ^[1]. That's why noise-induced hearing loss is usually permanent.

Here's how everyday sounds compare, using NIDCD's average levels ^[1]:

Sound	Average level (dBA)
Normal conversation	60 to 70
Movie theater	74 to 104
Motorcycles and dirt bikes	80 to 110
Headphones at max volume, sporting events, concerts	94 to 110
Sirens	110 to 129
Fireworks show	140 to 160

Safe exposure times: NIOSH vs. OSHA

Two federal agencies set noise numbers, and they don't match.

• NIOSH (the research agency) recommends an exposure limit of 85 dBA averaged over an 8-hour day ^[2]. For every 3 dBA increase, the safe time is cut in half ^[3].
• OSHA (the enforcement agency) sets the legal limit at 90 dBA over 8 hours, and halves the allowed time for every 5 dBA increase ^[4].

The NIOSH number is the safer guide for your own ears. The OSHA number is what employers can be held to.

Sound level (dBA)	NIOSH recommended max per day [3]	OSHA legal max per day [5]
85	8 hours	Triggers a hearing conservation program [5]
88	4 hours	Not listed
90	Not listed	8 hours
91	2 hours	Not listed
94	1 hour	Not listed
95	Not listed	4 hours
97	30 minutes	3 hours
100	15 minutes	2 hours
105	Not listed	1 hour
110	Not listed	30 minutes
115	Not listed	15 minutes or less

Look at the 100 dBA row. A loud concert or max-volume headphones can sit in that range ^[1]. NIOSH's limit there is 15 minutes ^[3].

Who gets noise-induced hearing loss

More people than you'd think. A CDC analysis of national hearing tests found that 24.4% of U.S. adults aged 20 to 69, roughly 39.4 million people, had a "notch" on their audiogram that signals noise damage ^[6].

It's not only a workplace problem. In that same study, 19.9% of adults who said they had no loud noise at work still had the notch ^[6]. NIDCD lists common off-the-job sources: target shooting, hunting, snowmobiling, high-volume earbuds or headphones, playing in a band, loud concerts, lawnmowers, leaf blowers and woodworking tools ^[1].

Most people don't know they have it. Among adults who rated their hearing as excellent or good, 23.5% had noise damage on testing ^[6].

Work is still a major source. NIOSH estimates about 27 million U.S. workers are exposed to hazardous noise on the job each year, and about 22 million are exposed to chemicals that can damage hearing ^[2]. About one in three adults exposed to loud noise at work had the noise notch, and 70% of those exposed said they never or seldom wore hearing protection ^[6].

Warning signs after a loud event

Two signals tell you a sound was too much:

• Muffled hearing. Some noise exposure causes temporary hearing loss that clears 16 to 48 hours later. NIDCD notes that research suggests there may still be lasting damage even after hearing seems to come back ^[1].
• Ringing, buzzing or roaring (tinnitus). It may fade, but it can persist ^[1]. If ringing sticks around, see our guide to tinnitus treatments with real evidence.

Repeated temporary shifts are a warning to cut exposure or improve protection. If hearing drops suddenly in one ear and doesn't come back, treat it as urgent: read what to do about sudden hearing loss.

Hearing protection that actually works

NIOSH lists three main types ^[7]:

Type	How it works
Earplugs	Fit into the ear canal. Can be formable foam, pre-formed, or custom-molded from an ear impression
Earmuffs	Cover the whole outer ear; held by a headband or attached to a hard hat
Canal caps	Cover the entrance to the ear canal; held by a lightweight band

Don't trust the box number alone. Hearing protector packaging carries a noise reduction rating (NRR). NIOSH says it "often does not reflect the actual protection provided for each worker" ^[7]. NIOSH also recommends one-on-one training on how to insert earplugs ^[7].

Fit testing is the real check. NIOSH calls individual fit testing "the best way to check if each worker is getting the amount of protection needed." It produces a Personal Attenuation Rating (PAR) for your ears and your protector ^[7]. Ask whether your employer or audiologist offers it.

Double up for the loudest jobs. NIOSH advises earmuffs over earplugs for noise at 100 dBA or greater, or for impulse sounds ^[7].

Don't overdo it at work. NIOSH suggests aiming to bring exposure down to roughly 75 to 85 dBA under protection and avoiding overprotection ^[7].

For everyday tips on concerts, headphones and yard work, see protecting your hearing at concerts, work and home.

Workplace hearing tests: what OSHA requires

If your noise exposure averages 85 dBA or more over an 8-hour shift, OSHA's general industry rule requires your employer to run a hearing conservation program ^[4][5].

Requirement	What the rule says
Noise monitoring	Employers must measure noise to identify workers at risk, and tell those workers the results [4]
Baseline hearing test	Within 6 months of first exposure at or above 85 dBA (up to 1 year if a mobile test van is used, with hearing protection required after 6 months) [5]
Annual retest	At least once a year after the baseline [5]
Standard threshold shift	A change from baseline averaging 10 dB or more at 2,000, 3,000 and 4,000 Hz in either ear triggers follow-up [4][5]
Hearing protectors	Provided at no cost, with a choice of suitable types [5]
Training	On noise hazards and protector use, repeated every year [5]
Noise controls	Engineering or administrative controls required above a 90 dBA 8-hour average [4]

Construction has its own OSHA standard, which requires noise controls and a continuing hearing conservation program when exposures exceed 90 dBA over 8 hours ^[4].

NIOSH goes further than the law: it recommends a yearly hearing test for anyone exposed to hazardous noise or ear-damaging chemicals at work ^[2].

What to do with your results. Ask for copies of your workplace audiograms and keep them; OSHA gives workers access to their monitoring records ^[4]. If a test shows a shift, ask about refitting your protection. Our guide to what happens at a hearing test explains the tests.

When to get your own hearing checked

The CDC report cites the American Speech-Language-Hearing Association's screening schedule for adults: every 10 years through age 50, then every 3 years ^[6]. Get checked sooner if:

• Hearing stays muffled more than a couple of days after a loud event
• Ringing in your ears doesn't fade
• You work around loud noise and haven't had a hearing test in the past year
• Family members say you're turning the TV up or missing conversations

A baseline test now gives you something to compare against later. Find a hearing provider near you.