Loud noise is present in many work environments. Think of people who work at airports and construction sites, or in factories, forestry and the resources sector, even at entertainment venues or schools packed with crowds. As hearing damage is permanent and irreversible, hearing protection — usually in the form of earplugs or earmuffs — is a key requirement across a swath of industries to prevent noise levels from damaging workers’ eardrums.
“Wherever machines generate sound is a potential for the requirement for hearing protection,” says Claudio Dente, president of Dentec Safety Specialists Inc., which distributes personal protective equipment (PPE) in Newmarket, Ontario. Dente cites pulp and paper, electrical utilities and automotive manufacturing as among the key sectors that require hearing-protection products.
Earplugs and earmuffs
Hearing protectors range from disposable earplugs to long-term earmuffs. They can be classified as active or passive: passive devices provide a constant level of sound reduction, which is convenient for environments that are continually noisy, while active devices use electronic means to augment or regulate noise reduction. Some active hearing protectors can even amplify sounds during quieter moments to enhance the worker’s awareness of the surrounding environment.
From simple foam earplugs to earmuffs that can be worn around the head or neck, Dentec offers a gamut of hearing-protection products through a line called Tasco, Dente says.
Also offering a broad range of products is 3M Canada, based in London, Ontario. In addition to the usual earplugs and earmuffs, 3M sells electronic headsets that allow workers to communicate with one another, while protecting their ears from excessive nearby noise.
“Probably the most popular hearing-protection device that we sell, or one of the more popular, is the foam earplugs,” says Bev Borst, advanced-development specialist with 3M. “It is an earplug that they roll down, put in their ear, and then replace it with another one the next time or a few uses later.” The company also sells reusable earplugs that last longer, in addition to earmuffs for long-term use, she adds.
Dente notes that comfort is an important factor when selecting the right auditory protection. “Wearing a hearing protector can be uncomfortable. If it is an earplug, you are going to insert it to your ear canal, and some people have sensitivity to inserting an earplug into their ear canal,” he explains.
“The issue about an earmuff is the amount of pressure that it applies to the side of the head in order to get protection. So that might cause some discomfort to people,” Dente adds. But the wide variety of products out there ensures that anyone should be able to find one that offers both comfort and proper protection, he adds.
First things first
One of the challenges of manufacturing hearing protectors is to shield a worker’s hearing without blocking out sounds that he or she needs to hear. For those who need to communicate constantly with colleagues and protect their hearing at the same time, Borst recommends active hearing-protection devices with electronic functions.
“They can just connect to their radio system or through their cell phones,” she says. That will enable them to communicate without having to remove their hearing protection. There are earmuffs and earplugs available with microphones that help accentuate speech frequency. “But the electronics also turn off when the noise level is dangerous,” Borst says. “People can easily communicate with someone, they can hear noises, they can actually adjust that volume, but the electronics also maintain a safe level, so that there is no damage to their hearing from communicating.”
Before making a purchase, an employer must measure the level of noise to which a worker is exposed, in order to determine how much protection is necessary.
Ashley Gaworski, product-line manager for hearing protection with MSA in Cranberry Township, Pennsylvania, says that a piece of equipment called a dosimeter is typically used. “There are manufacturers that make advanced ones, Bluetooth technology ones,” she explains. The dosimeter reading is applied into a special calculation that reveals the appropriate protection level, and three is subtracted from that to get the final reading.
CSA Group recommends three different selection methods for hearing protectors: the CSA Class, Octave Band Analysis or, most commonly, Noise Reduction Rating (NRR). The NRR is a concept that the Environmental Protection Agency in the United States defined in 1984. A protector with an NRR of 20, for example, reduces noise in a workspace by 20 decibels to the wearer’s ears.
One of the mistakes that employers often make, Dente notes, is overprotecting the worker. “If someone is working in an environment that has 90 decibels of sound and somebody selects a hearing protector that gives 30 NRR protection, that is going to get the noise level down to 60. That is too quiet.”
According to CSA, any noise-exposure level below 70 dBA is a sign of possible overprotection. In such conditions, workers may not be able to hear oncoming vehicles or moving machinery, or they may be oblivious to co-workers’ warning shouts. “Other issues can be that they might feel isolated,” Dente adds.
Gaworski suggests that workers who need to wear hard hats along with hearing protectors should equip themselves with the same brand of both products for a greater likelihood of compatibility. Although the CSA standard does not require hats and earmuffs to come from the same manufacturer, it does stress the importance of compatibility. With this in mind, MSA manufactures helmet-mounted hearing protectors that are specifically designed for MSA helmets.
As with all PPE, it is necessary to do routine checks of long-term hearing protectors in order to make sure that they are still working properly. Gaworski says that the foam and ceiling ring inside a pair of protective earmuffs should be replaced semiannually.
“Without doing that, you are possibly affecting the attenuation that you get, because they can deteriorate with oil and dirt and grime,” she points out.
It is also important to check regularly for cracks and other damage that may weaken the product’s ability. “If they are around chemicals, they need to make sure nothing is deteriorating,” Gaworski notes.
Dente recommends visual inspections, particularly of metal or plastic headbands that could crack or bend. “If it is metal,” he says, “people might bend it to loosen it, and you have got to be careful of that, because when you do that, it reduces the pressure of the ear, which reduces the protection.”
Ceiling rings are also vulnerable, he adds. “If you are wearing it steadily, the plain old synthetic material might have a reaction to sweat, perspiration, harden and so forth.”
Earplugs, on the other hand, are normally disposable after a few uses, although reusable earplugs made of rubber, plastic or silicone can last a lot longer if they are inspected regularly. “And again, it is a visual inspection,” Dente says. “If it is torn in any manner or soiled, you don’t want to put a soiled hearing protector in your ear.”
It is essential that earmuffs fit properly and that the cuffs seal tightly over the ears without interference from hair, glasses or jewellery. Borst points out the importance of fit-testing hearing protectors to ensure that they provide the right level of protection.
“There are other checks, like visually looking at the worker to make sure the earplug is well inserted into the ear or that the earmuff is situated properly over their head or on their hard hat,” Borst explains. But with the technology available today, “we can now fit-test earplugs and earmuffs and determine the worker’s Personal Attenuation Rating. We know exactly what that worker is getting from their hearing protection.”
As hearing is the primary sense that people use for communication, noise-induced hearing loss or any form of hearing loss can lead sufferers to withdraw from society to some degree, in part because they get weary of asking family and friends to repeat themselves in conversation. This is why it is so important for employers to protect their workers’ hearing on the job — with the proper equipment.
Jeff Cottrill is the editor of Canadian Occupational Health and Safety News.