Hearing Protection

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Hearing Protection Fit Testing

Real life performance of hearing protection is often different to specified performance. Under performance leads to Noise Induced Hearing Loss in later life and over performance places the wearer at risk of not being able to hear warning signs in the workplace.

In-ear hearing protection performance is measured in a laboratory, on sixteen test subjects using BS EN 13819-2:2020 with BS EN ISO 4869-2:1995 used to describe the calculations required to estimate the effectiveness. The results are averaged and expressed in dB.

Individual in-ear hearing protection products are then despatched with specification sheets which reflect those lab-based measurements. The specification sheet is designed to provide a guideline to effectiveness but does not provide a measure on individual performance.

In-ear hearing protection specification sheets contains the following information:

  1. APV (Assumed Protection Value)
    Several attenuation values across the frequency range.
  2. HML values
    High, mid and low frequency attenuation values calculated from APV values
  3. SNR
    Single Number Rating which is an overall attenuation rating.

 

An extract from a manufacturer’s specification sheet is shown below. 

Hearing Protection Earplugtests soundtable outline

This specification relates to custom-made product. If the protection is Universal-fit and there is no specification provided, then it is subject to BS EN 352-2:2020 which sets out a minimum level of attenuation based on HML values. 

Lab based averages for hearing protection specification gives rise to two problems

  • Real life performance is different to lab-based averages – view PDF and view pdf
  • Values calculated on averages cannot be used on individuals

A widely accepted hearing protection comparison measurement for individuals is known as PAR (Personal Attenuation Rating) and is directly comparable to SNR.

The hearing protection test report calculates a PAR and compares it with specification. It provides a quick, convenient, reliable, way to measure in-situ earplug performance thereby helping prevent Noise Induced Hearing Loss.

Earplugtest has been certified as fit-for-purpose as below:

“The general conclusion is that this system provides an acceptable means of a user testing their Personal Sound Attenuation (PSA) in order to assess the actual as opposed to specified level of attenuation provided by earplugs” 

– Professor C Barlow PhD MIOA

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