The short answer is "no." You cannot combine any pair of earmuffs with a hard hat and still get full protection.
Hardhat-mounted hearing protection (earmuffs or cup style) are a great piece of PPE. However, the hardhat mounting slots have to match the earmuff mounting clips. There has been some effort to provide hard hat mounting slots that are "universal" for earmuffs, but that is not the case with all brands and models.
There has been great progress in terms of the slot design and mounting hardware of muffs for full brim style hardhats. That was an issue in the past for that style of hardhat but isn't any more. Again though, you have to be certain that the style and type of hardhat you buy has that feature and has the type of muff rated for the noise exposure you or your workers are exposed to. The Noise Reduction Rating (NRR) is a critical factor in the selection of any hearing protection.
(Learn more in Hearing Protection PPE: Beyond the Basics.)
Noise is a well-known and documented hazard. Workers who are subjected to unprotected exposure to noise may experience both temporary and permanent levels of hearing loss. This is where PPE comes in. That said, hearing protection must match the exposure; a hearing conservation program is also a necessary part of your safety management system. This program must include baseline audiometric testing or threshold audiograms, followed by annual audiometric testing to help determine:
- Changes in hearing
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li>Effectiveness of noise controls, including PPE
(Learn more in How to Deal with Occupational Noise: Hearing Conservation Basics.)
First and foremost though, what is the noise exposure? According to the NSC Fundamentals of Industrial Hygiene text, the analysis of noise exposure during a detailed noise survey must provide the following critical factors:
- The A-weighted sound level
- The frequency composition of the sound or spectrum of the noise
- The duration and distribution of noise exposure during a typical workday
In terms of legislation, OSHA and NIOSH have addressed this subject in both General Regulation and NIHL (noise induced hearing loss) documentation. Canada has set out in the CSA Z1007: A new management standard from the Canadian Standards Association for the management of hearing loss prevention programs.
So, when it comes to ear muffs and hard hats, remember to match three things: the noise level exposure, the hardhat, and the earmuff that mounts to that hardhat shell. Manufacturers of hardhats do not allow end-user modifications to hardhats, so it is absolutely critical that you purchase muffs that fit the slots on the shell.
Depending on the noise level exposure, you may need to consider additional hearing protection. Also note that the actual protection offered by the PPE is dependent in large part on a good acoustical seal. That depends largely on the material used in the cushion part of the ear muff.
You may need special equipment and/or the services of an industrial hygienist and an audiologist. Good front-end work on this important health issue will get you and your company the best results.