Calculate your daily noise dose and hearing damage risk by NIOSH standards — enter sources, get your exposure percentage and protection advice.
📢 Noise Sources
Source 1
Source 2
📈 Daily Dose
0%
0%
of daily NIOSH limit used
Low Risk
Source 1 — safe daily limit:—
Source 2 — safe daily limit:—
✓No hearing protection required at this exposure level.
📊 dB Reference — Allowed Exposure Times
NIOSH uses a stricter 3-dB exchange rate (85 dB criterion). OSHA uses a 5-dB exchange rate (90 dB criterion). Both halve allowable time as decibels rise — NIOSH does so faster.
Noise Source
dB(A)
NIOSH Limit
OSHA Limit
Whisper / rustling leaves
30
No limit
No limit
Library / quiet office
50
No limit
No limit
Normal conversation
60
No limit
No limit
City traffic (inside car)
70
No limit
No limit
Vacuum cleaner
75
No limit
No limit
Busy restaurant / dishwasher
80
No limit
No limit
Power lawn mower
90
2 h 31 m
8 h
Motorcycle / truck engine
95
47 min
4 h
Tractor / jackhammer
100
15 min
2 h
Chainsaw / rock concert
110
1 m 29 s
30 min
Ambulance siren / nightclub
120
6 s
15 min
Jet engine (100 ft away)
130
< 1 s
—
Gunshot / firecracker
140
Immediate
—
NIOSH vs. OSHA: OSHA's permissible exposure limit (PEL) is 90 dB for 8 hours — it is a legal workplace minimum, not a health-safety optimum. NIOSH's recommended exposure limit (REL) is 85 dB for 8 hours and is based on health science showing that OSHA's limits still cause measurable hearing loss in workers over a career. This calculator uses the stricter NIOSH standard.
🛡️ Hearing Protection Guide
✅
No Protection Needed
Dose < 50%
Your daily noise dose is within a safe range. No hearing protection required, though limiting unnecessary loud exposure is always a good habit.
🔇
Earplugs
Dose 50–100%
You're approaching or at the daily limit. Foam or flanged earplugs reduce noise by 20–33 dB when correctly inserted. Roll, insert, and hold for 20–30 seconds until fully expanded.
Typical NRR: 25–33 dB
🎧
Earmuffs
Dose 100–200%
Your exposure exceeds the daily limit. Over-ear earmuffs provide consistent attenuation without correct-insertion skill. Cup must fully seal around the ear to be effective.
Typical NRR: 25–31 dB
⚠️
Dual Protection
Dose > 200%
Earplugs worn under earmuffs provides the maximum achievable protection (additional 5–10 dB over single protection alone). Leave the noisy environment as soon as possible.
Combined NRR: 30–36 dB effective
Understanding NRR (Noise Reduction Rating): The labeled NRR is tested under laboratory conditions. Real-world attenuation is typically half the NRR value for earplugs (so NRR 30 ≈ 15 dB of actual reduction). For earmuffs, real-world attenuation is about 75% of NRR. Dual protection adds roughly 5 dB over the higher-rated device alone — not a simple sum.
How to Use This Calculator
Select a noise source from the dropdown or choose Custom to enter a specific dB level.
Enter the duration in minutes per day you are exposed to that source.
Optionally add a second noise source to combine exposures (e.g., construction tools and traffic).
Read your daily dose percentage — values above 100% mean your hearing is at risk without protection.
Follow the ear protection recommendation shown below the gauge.
NIOSH Formula
Allowable exposure time at L dB:
T(L) = 8 × 2(85 − L) / 3 hours
Daily dose percentage:
Dose (%) = Σ (Ci / Ti) × 100
Where Ci is the actual exposure time and Ti is the allowable time at that dB level. A dose of 100% means you have reached the daily limit. NIOSH recommends keeping dose below 100% every day.
Glossary
dB(A)
A-weighted decibels — a frequency-weighted scale that approximates how the human ear perceives loudness. Standard for measuring noise exposure risk.
NIOSH
National Institute for Occupational Safety and Health (USA). Sets the recommended 85 dB / 8-hour exposure limit with a 3-dB exchange rate.
OSHA
Occupational Safety and Health Administration. The legally-enforceable PEL is 90 dB / 8 hours with a 5-dB exchange rate — less protective than NIOSH.
Exchange Rate
The dB increase that halves the allowed exposure time. NIOSH uses 3 dB (stricter); OSHA uses 5 dB (more permissive).
NRR
Noise Reduction Rating — the laboratory-measured attenuation of hearing protection in decibels. Real-world reduction is typically 50–75% of the labeled NRR.
NIHL
Noise-Induced Hearing Loss — permanent damage to cochlear hair cells from excessive sound exposure. It is preventable but irreversible.
Examples
Lawnmower for 1 hour
At 90 dB, NIOSH allows 2 hours 31 minutes. One hour = 1 / 2.52 hrs × 100 = 40% dose — Low Risk, no protection required.
Concert for 3 hours
At 110 dB, NIOSH allows only 1 min 29 s. Three hours exposure = 12,000%+ dose — Danger level, ear protection is critical.
Construction worker (mixed)
Power tools at 90 dB for 2 hours (79% dose) + chainsaw at 110 dB for 10 min (671% dose) = 750% total dose — Immediate hearing damage risk without dual protection.
Understanding Noise-Induced Hearing Loss
Noise-induced hearing loss (NIHL) is one of the most common preventable disabilities. Approximately 17% of US adults aged 20–69 have permanent hearing damage from excessive noise exposure, according to NIOSH. Unlike sudden hearing loss from trauma, NIHL accumulates gradually — making it easy to ignore until significant damage has already occurred.
The inner ear contains roughly 15,000 tiny hair cells (stereocilia) in the cochlea. These cells convert sound vibrations into electrical signals sent to the brain. Loud noise physically damages or destroys these cells. Unlike most cells in the body, cochlear hair cells do not regenerate. Each loud exposure permanently removes some capacity.
Early signs of NIHL include temporary threshold shifts (muffled hearing, tinnitus after a concert that resolves overnight) and difficulty understanding speech in noisy environments. These early warnings are often dismissed — but they indicate that damage is accumulating.
The good news: NIHL is entirely preventable. Simply keeping daily dose below 100%, using appropriate ear protection during loud activities, and taking quiet breaks reduces lifetime risk dramatically.
Frequently Asked Questions
How loud is too loud?
NIOSH recommends limiting exposure to 85 dB(A) for no more than 8 hours per day. Sounds at or below 70 dB are generally considered safe for unlimited exposure. As a rule of thumb: if you have to raise your voice to be heard at arm's length, the noise is probably above 85 dB.
How long can I be exposed to 85 dB?
At 85 dB, NIOSH allows 8 hours before the daily dose reaches 100%. Every 3 dB increase halves the allowed time: 88 dB → 4 hours, 91 dB → 2 hours, 94 dB → 1 hour, 97 dB → 30 minutes. At 110 dB (a typical chainsaw or rock concert) the limit is only 1 minute 29 seconds.
What is noise-induced hearing loss?
Noise-induced hearing loss (NIHL) is permanent damage to the hair cells in the inner ear caused by loud sound. These cells convert vibrations into nerve signals — once destroyed, they do not grow back. NIHL is preventable but not reversible, making ear protection and dose management the only real defense.
What is the difference between NIOSH and OSHA noise standards?
NIOSH uses an 85 dB criterion level with a 3-dB exchange rate (halves allowed time every 3 dB). OSHA's permissible exposure limit is 90 dB with a 5-dB exchange rate. OSHA's standard is a legal floor for workplaces, not a health optimum — decades of research show it still causes hearing loss in workers over a full career. This calculator uses NIOSH limits because they better protect long-term hearing health.
Can noise exposure add up across different sources?
Yes. The daily dose formula sums fractional exposures from all sources. If you work near traffic (80 dB, 8 hours = 32% dose) and then attend a loud event (100 dB, 30 min = 133% dose), your combined dose exceeds 165% — well into the "High Risk" zone even though neither source alone might seem alarming.