Daily Noise Dose Calculator

How a Daily Noise Dose Works

Hearing damage is cumulative and dose-dependent, which is why the useful question is not “is this loud?” but “how much of today’s budget did that use?”

NIOSH (National Institute for Occupational Safety and Health) and OSHA (Occupational Safety and Health Administration) both express that budget as a time-intensity trade-off: every 3 dB increase (NIOSH) or 5 dB increase (OSHA) halves the safe exposure time. This page uses the NIOSH 3 dB rule, which is the more protective of the two and the one hearing scientists prefer.

A dose of 100% means you have used the whole day’s allowance. Going over it does not cause immediate injury, and staying under it does not guarantee you are fine forever, but over years the dose is what predicts the damage.

NIOSH Permissible Exposure Time Formula:

Safe Duration (hours) = 8 / 2^((dB − 85) / 3)

Where 85 dB is the NIOSH recommended exposure limit for an 8-hour day.

Safe Exposure Reference (NIOSH standard):

The 80 dB floor:

NIOSH does not count exposure below 80 dBA toward a daily dose at all, which is why the 75 dB row is marked that way even though the formula still produces a number for it. 80 dB itself is on the floor and does count. Above 80 dB the dose accumulates, and it is a daily budget shared across everything you do that day. A loud commute and a loud evening draw on the same 100%.

Worked Example:

Concert venue at 105 dB:

• Safe time = 8 / 2^((105−85)/3) = 8 / 2^6.67 = 8 / 101.6 = 4.7 minutes

Real-World Sound Levels:

• Conversation: 60–65 dB
• Heavy traffic: 85 dB
• Lawn mower: 90 dB
• Rock concert: 100–120 dB
• Gunshot: 140–165 dB

Protection Options:

The NRR (Noise Reduction Rating) printed on the box is a laboratory figure measured on a perfectly fitted plug, and almost nobody fits them perfectly. OSHA’s field derating takes 7 dB off the label and halves the rest, (NRR − 7) ÷ 2, and it is what the site’s other noise calculators use too:

• Foam earplugs: about 11 to 13 dB, against a labelled NRR of 29 to 33
• Earmuffs: about 8.5 to 10.5 dB, against a labelled 24 to 28. Less than foam, which surprises most people
• Both together: the higher of the two, derated, plus 5 dB. About 17.5 dB for plugs rated 32 under any muff
• Custom musician plugs: 9 to 25 dB with a flat response, so music still sounds like music

Twelve decibels does not sound like much next to 32. It is still worth about 16 times more exposure time, because of the same 3 dB doubling that makes the safe times collapse in the first place.