SNR Levels for Ear Defenders

What is SNR?

SNR (Single Number Rating) is a standard measurement used in the UK and EU to indicate how much a hearing protector can reduce noise exposure. It provides a simplified average of the product’s noise reduction across a range of frequencies.

How SNR Works with Ear Defenders

SNR works by subtracting its value from the average workplace noise level to estimate your protected exposure. For example, if your environment is 100 dB and your ear defenders are rated SNR 30, your approximate exposure is 70 dB. This helps employers ensure workers are kept below legal noise thresholds, like the 85 dB(A) daily limit. It's important to remember that SNR values are based on lab tests, and actual protection may vary due to fit, wear time, and compatibility with other PPE.

Choosing the correct SNR for your Environment

The best SNR levels for your environment depend on the noise levels – too low and you’ll be under-protected, too high and you may block out important sounds.

  • For environments around 85–90 dB(A), an SNR of 20–25 is usually sufficient.
  • Workplaces above 95 dB(A), like engine bays or heavy manufacturing, typically require SNRs of 30 or more.
  • Overprotecting can be a safety risk in itself, especially where workers need to hear alarms or instructions.

How SNR is Tested?

SNR levels are tested using controlled sound environments and human test subjects in laboratories under the EN 352 standard. During the test, participants are exposed to specific noise frequencies with and without hearing protection to calculate how much sound is reduced.

This testing produces HML values (High, Medium, Low frequencies) which are then used to calculate the overall SNR figure. All certified hearing protection products must display UKCA (UK Conformity Assessed) or CE (Conformité Européenne) markings to show compliance with the relevant safety directives.

There are many HSE registered Noise Survey specialists that can visit your place of work for a full Noise Assessment. This will ensure you have all of the correct data allowing the procurement of the correct hearing protection.
When deploying Ear Defence you should be aiming for between 70db-80db at the ear. This is a comfortable and normal working noise level.
This maybe the case but are they being inserted into the ear canal correctly to give the optimum hearing defence? By deploying an ear defender with a headband there can be little doubt that the user is protected at all times.
When purchasing or even renting technical Ear Defence it is difficult to substantiate the integrity or the certified performance of a product with an unknown history so consequently this is something that we discourage.