3M hearing protection fit testing: what, why and how

The team at 3M know the importance of hearing safety and testing, introducing the 3MTM E-A-RfitTM Dual-Ear Validation System to improve worker health and safety on site.

The adoption of individual hearing protector fit testing is steadily gaining traction in industry as a powerful tool for helping to improve occupational hearing conservation programs.

The driving force behind this growing trend is the ability to accurately estimate the attenuation a given hearing protector provides for an individual, in contrast to the traditional approach of relying solely on single number ratings.

The benefits of hearing protector fit testing are being realised by employers and workers alike, and fit testing has become a recommended best practice in hearing loss prevention.

How does hearing protector fit testing work?

There are a variety of FAES technologies available on the market. The 3MTM E-A-RfitTM Dual-Ear Validation System is based on field microphone-in-real ear (F-MIRE) technology. The system consists of a specially designed loudspeaker equipped with a digital signal processor that allows for a consistent presentation of the test signal and real-time communication between the microphones, speaker and software.

The dual-element microphone assembly attaches to specially probed hearing protectors to allow measurement of the sound level inside the test subject’s ear canal while the hearing protector is worn.

The “in-ear” sound level is simultaneously compared to the sound level just outside the hearing protector, as measured by the external microphone. The measured difference between the internal and external sound levels represents the noise attenuation in decibels.

The 3MTM E-A-RfitTM Dual-Ear Validation System is an objective measurement system which means it does not depend on a response from the person being tested. This allows 3MTM E-A-RfitTM Dual-Ear Validation System to test both ears across numerous frequencies simultaneously in less than 5 seconds.

It also allows for normal background noise, up to 85 dB (A) or 91 dB (C), to be present during the testing as compared to other subjective FAES systems, which require quieter test environments. The 3MTM E-A-RfitTM Dual-Ear Validation System can also test a range of 3M earmuffs and certain communications headsets.

What is a PAR?

The ‘Personal Attenuation Rating’, or PAR, for a hearing protector is the noise attenuation achieved by the individual being tested. In simple terms, it is the difference in decibels between the sound levels on the inside of the hearing protector and just outside the hearing protector.

PARs tell us how much attenuation a particular hearing protector model is providing when fitted in the actual user’s ear, by the actual user.

Key benefits of fit testing

Why use hearing protector fit test systems, such as the 3MTM E-A-RfitTM Dual-Ear Validation System? Incorporating fit testing into a Hearing Conservation Program can offer a multitude of benefits. For example, conducting hearing protector fit testing helps employers to:

  1. Identify workers with poorly fitting hearing protectors before the worker develops hearing loss.
  2. Create a unique training opportunity where workers an experience how correctly fitting hearing protectors impacts protection:
    – PAR results are seen immediately following test.
    – One-on-one training targets the specific fitting issues observed.
    – PAR improvements are seen immediately after re-training and re-inserting the ear plug correctly.
    – Workers can feel and hear the difference when their hearing protectors are properly inserted.
  3. Refine hearing protector selection based on individually validated protection levels.
  4. Supplement hearing loss intervention strategies by helping to ensure workers with hearing shifts are properly trained and protected.
  5. Implement pro-active, best practices approach to hearing loss prevention.

Fit testing is here to stay

Fit testing hearing protection can make a difference. It can change how people use hearing protection, think about hearing protection, and are protected by hearing protection. When it comes to attenuation, why guess when you can know?

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