23/03/2024
How to understand attenuation for ear defenders
Hearing protectors form a physical barrier between noise energy and the inner ear. Passing through the ear defender cup or earplug causes the sound to lose energy, and a lower energy sound means a quieter sound. This process of losing noise energy is called attenuation, and different products offer different attenuation levels.
Attenuation levels
The attenuation performance of hearing protectors ranges widely. The aim of an ear defender or earplug is to bring the noise level to the region of 75dB(A) to 80dB(A). Higher energy noise requires a higher attenuation level than a lower energy noise. Products are therefore available with a range of performance levels to offer adequate protection.
Overprotection
Noise is one of the only risks against which it is possible to overprotect operatives in the workplace. While high level noise is harmful, other sounds such as speech, warning signals, or approaching vehicles are vital for safe and productive working.
The product with the highest attenuation level is not always the most suitable as the attenuation performance can isolate the worker and put them at risk of an accident.
A hearing protector with performance closest to the required attenuation level should be selected, to provide adequate protection without presenting additional risk.
Finding attenuation information for hearing protectors
There are several ways to identify and compare the attenuation performance of a hearing protector:
SNR (Simplified Noise Level Reduction, also referred to as Single Number Rating)
The SNR level achieved in testing can be used as a general means of comparing the protection level of different products. The SNR value can be subtracted from the overall noise level to calculate the sound pressure at the ear when wearing that particular hearing protector.
SNR is marked products or packaging, detailed in user instructions, available on request from manufacturers, and often shown in product marketing materials.
H, M, L performance
Hearing protection testing results are assessed to determine performance based on 3 parameters, H, M, and L.
The terms refer to the noise reduction of the chosen hearing protector at High, Medium and Low frequencies.
The H,M,L data provides a method of estimating the attenuation offered by a hearing protection product at each of the frequencies.
H,M,L information is detailed in user instructions supplied with products and available on request from hearing protection manufacturers.
Full attenuation data
The full attenuation data for hearing protectors shows the performance of the product against a range of frequencies: 63Hz, 125Hz, 250Hz, 500Hz, 1000Hz, 2000Hz, 4000Hz, and 8000Hz.
Full attenuation performance data can be required for hearing protector calculators, to select appropriate ear defenders or earplugs for measured noise levels.
This information is available on request from hearing protection manufacturers and detailed in the user instructions supplied with products.
