td = maximum duration time at 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)
TWA = Time Weighted Average noise level (dB)
Daily noise dose as an 8-hr TWA for different daily noise doses:
|Daily Noise Dose|
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
Room acoustics and acoustic properties, decibel A, B and C, Noise Rating (NR) curves, sound transmission, sound pressure, sound intensity and sound attenuation.
The NIOSH noise Recommended Exposure Limit - REL - for occupational noise
Exposure to noise should be controlled so that it is less than a maximum combination of exposure level and duration.
Background noise frequencies that interferes with speech.
Shift in hearing threshold for men and women vs. age.
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