Safe Listening Time Calculator (Noise Exposure, NIOSH and OSHA)
How long you can listen or work at a sound level each day before reaching the noise exposure limit, and what dose your day adds up to.
Results
The dashed line marks the value you entered.
What this tool does
Hearing damage depends on both loudness and time, and every 3 dB more sound doubles the energy. The US National Institute for Occupational Safety and Health recommends a limit of 85 dBA for 8 hours with a 3 dB exchange rate: at 91 dBA the safe time is 2 hours, at 100 dBA about 15 minutes. The older OSHA legal limit is 90 dBA for 8 hours, halving every 5 dB, which is more permissive. Earphones turned up to maximum can reach around 100 dB, so an hour a day may already be too much. Doses from different parts of the day add up, and the sound level must be measured at the ear, not read from a volume slider.
Formula
NIOSH: T = 8 ÷ 2^((L − 85) ÷ 3) hours · OSHA: T = 8 ÷ 2^((L − 90) ÷ 5) hours · dose = exposure time ÷ T × 100
Variables
| Symbol | Meaning | Unit |
|---|---|---|
lv | Average sound level at your ear | dBA |
hr | Time exposed per day | h |
TN | Permissible time per day (NIOSH: 85 dBA for 8 h, halving every 3 dB) | h |
TM | The same in minutes | min |
DN | Daily noise dose by NIOSH (100 % is the limit) | % |
TO | Permissible time per day (OSHA: 90 dBA for 8 h, halving every 5 dB) | h |
DO | Daily noise dose by OSHA (100 % is the limit) | % |
Worked example
- Average sound level at your ear90 dBA
- Time exposed per day2 h
- Permissible time per day (NIOSH: 85 dBA for 8 h, halving every 3 dB)2.52 h
- The same in minutes151 min
- Daily noise dose by NIOSH (100 % is the limit)79 %
- Permissible time per day (OSHA: 90 dBA for 8 h, halving every 5 dB)8.00 h
- Daily noise dose by OSHA (100 % is the limit)25 %
Limitations
- This tool is informational only. It does not diagnose, treat or replace a qualified health professional. Speak to a doctor before making decisions about your health.
- For work that must comply with a standard or be signed off, check the result against the applicable code and have it reviewed by a qualified engineer.