How long can a person endure a certain noise level before hearing impairment occurs?


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One way that noise can permanently damage your hearing is by a single brief exposure to a high noise level, such as a firecracker going off near your ear. But hearing damage can also occur gradually at much lower levels of noise, if there is enough exposure over time.

To protect your hearing, you'll want to limit your exposure to these moderately high noise levels as well, and give your ears a chance to recover after any period of noise exposure.



Calculate SPL

Permissible time  



 

Calculate Time

Permissible SPL  dB



 


Accepted guidelines for recommended permissible exposure time for continuous time weighted average noise, according to NIOSH-AINSI and CDC. For every 3 dB sound pressure level (SPL) over 85 dB, the permissible exposure time is cut in half − before damage to our hearing can occur.

  • NIOSH = National Institute for Occupational Safety and Health.
  • CDC = Centers for Disease Control and Prevention.
  • OSHA = Occupational Safety and Health Administration.
  • NIOSH represents the use of an 8-hour exposure of noise at 85 dBA and a 3 dBA doubling rate, to determine the noise dose.
  • OSHA represents the use of an 8-hour exposure of noise at 90 dBA and a 5 dBA doubling rate, which does not protect many workers from hearing loss over their whole working lifetime.

Permissible Exposure Time Guidelines


 Sound Pressure Level   Sound pressure   Permissible Exposure Time 
115 dB 11.2 Pa 0.46875 minutes (~30 sec)
112 dB 7.96 Pa 0.9375 minutes (~1 min)
109 dB 5.64 Pa 1.875 minutes (< 2 min)
106 dB 3.99 Pa 3.75 minutes (< 4 min)
103 dB 2.83 Pa 7.5 minutes
100 dB 2.00 Pa 15 minutes
  97 dB 1.42 Pa 30 minutes
  94 dB − − − − − − − − − − 1.00 Pa − − − − − − − − 1 hour − − − − − − − − − − −
  91 dB 0.71 Pa 2 hours
  88 dB 0.50 Pa 4 hours
  85 dB 0.36 Pa 8 hours
  82 dB 0.25 Pa 16 hours




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