Standard explainer · EN 352
Noise injury is permanent, invisible and entirely preventable — and the kit that prevents it is labelled with one number almost nobody can explain. Here's what SNR means, how the EN 352 family divides up, and the counterintuitive rule: you can wear too much hearing protection.
The number
SNR (Single Number Rating) is the protector's average attenuation in decibels: workplace noise level minus SNR ≈ the level at your ear. A 100 dB workshop with SNR 27 muffs puts roughly 73 dB at the ear — comfortably under the levels UK regulations act on (action values at 80 and 85 dB(A) daily exposure).
The counterintuitive part: aim for 70–80 dB at the ear, not as low as possible. Over-protection isolates — you can't hear the forklift horn, the shouted warning, the change in machine note that says something's wrong — and it drives people to remove protection entirely, which destroys the arithmetic. An SNR 35 plug in an 88 dB environment is the wrong buy; an SNR 20 is right.
The family
| Part | Covers | Where it wins |
|---|---|---|
| EN 352-1 | Earmuffs (headband) | Intermittent noise — on and off ten times an hour without fuss |
| EN 352-2 | Earplugs (disposable, reusable, banded) | All-day wear, hot work, tight spaces; hygiene discipline required |
| EN 352-3 | Helmet-mounted muffs | Construction and forestry — helmet and muffs as one system |
| Higher parts | Level-dependent & electronic types | Impulse noise and communication needs — specialist buying |
The realities
Questions
Single Number Rating — the protector's average noise reduction in decibels. Subtract it from the workplace noise level to estimate the level at your ear: 100 dB noise with SNR 27 muffs is roughly 73 dB at the ear. Pick SNR to land between about 70 and 80 dB — protected, but not isolated.
Neither universally. Muffs (EN 352-1) win for intermittent noise because they go on and off easily and their condition is visible. Plugs (EN 352-2) win for all-day wear, heat, confined spaces and under helmets — if inserted properly, which is a trained skill. Many sites use both: plugs for the shift, muffs for visitors.
Yes — over-protection cuts you off from alarms, vehicle horns and speech, and makes people remove the protection to communicate, defeating it entirely. The target is roughly 70–80 dB at the ear, not the biggest SNR on the shelf.
Everything decoded here is stocked as certified garments and PPE, embroidered where it makes sense.