For those of us who regularly use dust masks for work, you’ve probably heard about respirator fit testing before (if you haven’t, check out this site).

But have you heard of earplug fit testing?

Earplugs, earmuffs and other hearing protection is used to reduce the noise that reaches your ears – to a safe level.  Officially this is a device that ‘reduces the unwanted effects of sound’ (Standards Australia & Standards New Zealand 2002) – For those of us in Australia, they also need to meet the requirements of AS/NZS 1270:2002.

To select which hearing protectors to use, one common method involves looking at:

1/  how loud the work environment is, and

2/ how much the hearing protection will reduce unwanted noise (i.e. the ‘Classification method’, AS/NZS 1269.3:2005).

In the Australian system, earplugs and other hearing protectors are rated from Class 1 to Class 5, with Class 5 hearing protectors giving the biggest reduction in noise (i.e. the biggest ‘attenuation’).

……However……

The problem with one-size-fits-all

There is emerging evidence that the classification system (and other manufacturer-reported measures of attenuation) may not actually represent the protection that real workers will get from their earplugs (McBride et al. 2013, Ryan et al. 2017, Berger et al. 2011 and Berger 1993, as cited in Lee et al. 2022).  A recent Australian study found that, out of 65 participating workers from a major hazard facility, none of them were able to achieve the SLC₈₀^[1] ratings of the typical class 4 earplugs worn (Lee et al. 2022).

Most of us recognise that ‘one size fits all’ clothing, shoes, gloves etc. may not actually fit everyone well.  With different ear canal shapes, ear sizes, as well as user dexterity and hearing protection insertion technique, It’s unlikely that we’ll all achieve the same fit with the same earplug (Chiou et al. 2016; Lee et al. 2022; Rocha et al. 2015; Salmani Nodoushan et al. 2014; Samelli et al. 2018).

A similar problem is encountered with respiratory protection; this is why the Australian Standards require users to undergo regular respirator fit-testing to verify that the respirator will provide effective protection from airborne hazards (Standards Australia & Standards New Zealand 2009).

So, what is hearing protection fit testing?

Currently, there are a few fit testing systems that are available commercially, with a few different methods available to test the attenuation and fit of hearing protection.

One system that we use, CAPA©, is similar to conducting an audiometric test with, and without, earplugs worn (i.e. ‘Real-Ear Attenuation at Threshold’-based method).  Using this method, we can calculate the noise reduction that is achieved when an individual uses a specific earplug.  The best part? We can test any earplug or earmold that fits beneath a set of headphones using this method.

We can also assess 3M™ specific earplugs using the 3M™ E-A-Rfit™ Dual-Ear Validation System, which measures the noise level outside and inside the earplug worn by the individual.  This test occurs over a matter of seconds.