How Fit-Testing Earplugs Helped Boost Hearing Protection

How Fit-Testing Earplugs Helped Boost Hearing Protection

In the oil and gas sector, where piercing noises are very common, nearly half of the workers suffer from noise-induced hearing loss (NIHL), according  to WorkSafeBC. Statistics show the percentage of workers with signs of hearing loss has increased by 12% over the last five years, from 33% in 2012 to 45% in 2017.

Meanwhile, Honeywell succeeded in substantially improving the hearing protection of workers at Beerenberg, a major oil producer in Norway. Find out how Honeywell’s fit-testing training helped Beerenberg workers reduce their exposure to NIHL risks.

What is hearing protection fit testing?

Hearing protector fit-testing provides an individual worker with a Personal Attenuation Rating (PAR) and helps the worker learn when the hearing protector is fit correctly. The PAR is a direct measurement of hearing protector attenuation on an individual worker; it is not an estimate based on the attenuation number printed the hearing protector package. The PAR can be subtracted from the known workplace noise level to yield a realistic and more representative personal protected noise exposure level.

The National Hearing Conservation Association (NHCA) and The Occupational Safety and Health Administration (OSHA) have endorsed fit testing as a recommended best practice in reducing NIHL.

Does wearing an earplug protect from NIHL?

“It has been repeatedly proven that simply wearing any earplug doesn’t necessarily protect from noise-induced hearing loss,” tells Kim Deason, PPE Solution Sales Manager at Honeywell Industrial Safety. 

“An earplug that is too small allows noise to flow right around it, so it offers little to no protection. Wearing one that is too large, pushing [itself] out when it recovers, isn’t doing a better job either. "

"Workers should also pay attention to choose the correct size. In the field, I have seen earplugs cut in half lengthwise or shortened, in hopes of a better fit. However, altering an earplug, or any PPE for that matter, is throwing away any guarantee that it will work the way it was designed to. Fortunately, there are many sizes and shapes of earplugs available to suit each unique ear canal. One-size-earplug-fits-all is a myth”, Deason concludes.

Fit-testing hearing protection ensures both an appropriate choice of hearing protection and professional training on proper techniques to wear.  

A fit-testing success story from Norway

When choosing hearing protection for workers, employers still rely on the Single Number Rating (SNR) in Europe or the Noise Reduction Rating (NRR) in North America, which are achievable under certain ideal laboratory conditions. These ratings are not the actual attenuation most workers will achieve. Noise reduction in the field can range from over 40 decibels (dB) to zero dB depending on whether a worker is using earplugs of the appropriate size and whether they are inserted correctly.

Beerenberg decided to find out what level of individual attenuation their workers were achieving with their earplugs by conducting fit testing using Honeywell’s VeriPRO® fit testing system. Two hundred eighty-eight workers were asked to choose their preferred earplugs from a selection of different models and sizes. Then, without any guidance on how to insert the plugs, their attenuation levels were tested. 

Four out of ten employees achieved attenuation levels below the minimum attenuation criterion of 16 dB, and two out of ten workers achieved only 10 dB. 

Workers were provided with one-on-one advice and a face-to-face demonstration on how to best fit their foam earplugs in three simple steps:

1. Roll the earplugs into a small cylinder without creases or wrinkles. 

2. Pull the ear (pinna) outwards to straighten the ear canal with the freehand, so that the earplug can be deeply inserted into the ear canal. 

3. Hold the earplug in place for a few seconds while it expands to seal the ear canal.

The training also revealed whether the worker needed a different size of style of earplug to achieve the best fit. With the right fit, the proportion of workers with poor attenuation performance dropped to just over 5 percent.

Ninety-seven percent of workers stated that they found the individual guidance on how to insert earplugs either useful or extremely useful.

The fit-testing experience increased the awareness of the importance of selecting and fitting earplugs correctly. Nearly 80 percent of workers said that they had become more conscious about inserting the earplugs correctly and almost half of them said that they had experienced improved noise attenuation. Almost 70 percent said that the training made using earplugs better.

The long-term benefits of fit-testing

Although encouraging, the results of training need to be effective over the long-term as NIHL develops gradually and noise attenuation is important every day, for a long time. Therefore, a follow-up study was conducted a year after the initial fit testing and training.

The target group consisted of 41 workers with initial attenuation levels lower than 16 dB during the first test. Just like in the first test, they were asked to choose the earplugs they typically used and insert them as they use to do, without any guidance.

Twenty of the 41 workers achieved results over the 16-dB criterion level, while 21 had fallen below. However, this second fit testing also showed an increase in the average PAR, from 8.9 dB to 17.1 dB. If average values are considered, the employees still retained an improvement in their PARs 6-12 months after the training.

However, the 17.1 dB average value from the follow-up test was lower than the 22.5-dB average PAR obtained immediately following the initial training. This means that even though the workers had achieved significant improvement after training, the average attenuation had fallen slightly during the year. Workers with scores below the criterion level received new training, which led to an impressive noise attenuation score of 26.9 dB.

Why don’t workers practice inserting the earplugs correctly?

The perceived usefulness of the training was assessed to answer this question, based on the assumption that workers who experienced a major benefit from the training and fit testing were more inclined to maintain the skill of inserting the earplug correctly. A variable was developed to measure the change in attenuation after the second fit testing as well as before, calculated as the difference between the values following the first fit testing session and those carried out after the second fit-testing training. This test showed that for the workers who achieved less than a 10-dB increase in PAR after the initial training, the average PAR was now only 1.5 dB higher. 

The workers who experienced an increase of 10 dB or more following the initial fit testing and training continued to achieve a significantly higher average PAR of 20.7 dB.

The role of individual training in increasing hearing protection

Tests led to a clear conclusion. 

Through simple steps such as individual face-to-face training, fit testing, and possibly changing the type of earplugs used, employers can significantly increase the level of hearing protection offered to workers.

Adopting a personalized, individual approach to hearing loss prevention can also educate and motivate workers, helping them discover the importance of using properly fitted earplugs and inserting them correctly.

The findings showed that more than half of the workers who initially received low attenuation fall back to below the criterion attenuation level 6-12 months after receiving training. Those with good results during the training continued to achieve good attenuation levels. 

The conclusion is that refreshment training with fit testing, continuous focus on hearing loss prevention, and having an adequate selection of hearing protection device styles and sizes, are crucial for ensuring the proposer's use of appropriate hearing protection and preventing occupational NIHL.