Hearing protection and decibel reduction 2

[Safetyranger]

We use ear plugs and ear muffs in combination at more than one process. Neither type of protection has a high enough NRR to bring the decibels down to a safe level, so we combine them. Does anyone know if this is an approved practice or what could be used instead? Is this issue cited specifically in OSHA, NIOSH, ANSI, etc?

 

[mcgyvr]

Typically the combination of ear plugs and muffs are required to achieve a NRR over 34. This is deemed acceptable provided that you train (and document) your employees that both are required to achieve adequate hearing protection.

http://www.cdc.gov/niosh/docs/98-126/chap6.html

 

[chicopee]

The practice that you are describing was used by air force personnel working on jet engines in the 60's. To the best of my knowledge it is still used, however, if I remember correctly, hearing protection becomes of no value for sound levels above 120 decibels because of bone conduction.

 

[safetydan]

The combination of both plugs and muffs is well established and endorsed if needed to achieve the required level of reduction.

chicopee, I've never seen any documentation that states hearing protection is not effective over 120 dB. There are many industrial/construction/military sites that have >120 dB and not had noise induced hearing loss. If you know of any published reports, please post. Thanks.