Noise - Maximum Daily Dose Level
Maximum daily noise dose level when exposed to periods with different levels.
When the daily noise exposure consists of periods of different noise levels, the daily dose can be calculated as:
D = ( te1 / td1 + te2 / td2 + ... + ten / tdn ) 100% (1)
where
D = daily noise exposure (%)
te = exposure time at a specified noise level (min)
According the National Institute for Occupational Safety - NIOSH - the daily dose level - D - should not equal or exceed 100%.
The daily dose can be converted to an 8-hr Time-Weighted Average -TWA by the formula
TWA = 10 log (D / 100) + 85 (2)
where
TWA = Time Weighted Average noise level (dB)
Daily noise dose as an 8-hr TWA for different daily noise doses:
| Daily Noise Dose (%) | 8-hr TWA (dB(A)) |
|---|---|
| 20 | 78.0 |
| 30 | 79.8 |
| 40 | 81.0 |
| 50 | 82.0 |
| 60 | 82.8 |
| 70 | 83.5 |
| 80 | 84.0 |
| 90 | 84.5 |
| 100 | 85.0 |
| 200 | 88.0 |
| 400 | 91.0 |
| 600 | 92.8 |
| 800 | 94.0 |
| 1,000 | 95.0 |
| 1,500 | 96.8 |
| 2,000 | 98.0 |
| 4,000 | 101.0 |
| 6,000 | 102.8 |
| 8,000 | 104.0 |
| 10,000 | 105.0 |
| 20,000 | 108.0 |
| 40,000 | 111.0 |
| 60,000 | 112.8 |
| 80,000 | 114.0 |
| 100,000 | 115.0 |
| 150,000 | 116.8 |
| 200,000 | 118.0 |
| 400,000 | 121.0 |
| 600,000 | 122.8 |
| 800,000 | 124.0 |
| 1,000,000 | 125.0 |
| 2,000,000 | 128.0 |
| 4,000,000 | 131.0 |
| 6,000,000 | 132.8 |
| 8,000,000 | 134.0 |
| 10,000,000 | 135.0 |
| 20,000,000 | 138.0 |
Example - Daily Noise Dose Level
During a working day a person is exposed to 100 dB in 5 minutes and 94 dB in 30 minutes.
The maximum noise exposure time for 100 dB is 15 minutes and for 94 dB 60 minutes.
The daily dose can be calculated as
D = ((5 min) / (15 min) + (30 min) / (60 min)) 100%
= 83 %
The Time-Weighted Average -TWA can be calculated as
TWA = 10 log (83 / 100) + 85
= 84 dB
Related Topics
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Acoustics
Room acoustics and acoustic properties, decibel A, B and C, Noise Rating (NR) curves, sound transmission, sound pressure, sound intensity and sound attenuation.
Related Documents
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Noise - Recommended Exposure Limits (REL)
The NIOSH noise Recommended Exposure Limit - REL - for occupational noise -
Noise Exposure - Permissible Levels and Duration
Exposure to noise should be controlled so that it is less than a maximum combination of exposure level and duration. -
SIL - the Speech Interference Levels
Background noise frequencies that interferes with speech. -
Sound - Hearing Threshold vs. Age
Shift in hearing threshold for men and women vs. age.
