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Standards guide · Hearing

Hearing protection explained

Noise damage is permanent. It builds up slowly.

  • EN 352-1:2020
  • EN 352-2:2020
  • EN 352-3:2020

Read this ifYou see SNR 30 or H M L

How loud is too loud?

Daily (8 hour) exposure and peak values. Same numbers in GB, NI and Ireland.

  1. 80dB(A)

    Lower action value

    Peak 135 dB(C)

    Assess risk, give information and training, make hearing protection available.

  2. 85dB(A)

    Upper action value

    Peak 137 dB(C)

    Noise control programme, hearing protection zones, protection must be worn, health surveillance.

  3. 87dB(A)

    Exposure limit value

    Peak 140 dB(C)

    Must not be exceeded, taking the hearing protection into account.

  • 80 dB(A) - offer protection and training.
  • 85 dB(A) - protection must be worn. Mark the zone.
  • 87 dB(A) - the limit at the ear. Never go over.
  • Rule of thumb (HSE): if you have to raise your voice to talk to someone 2 m away, get the noise assessed.

Decode the label

Example: SNR 30 dB H 32 M 27 L 20.

EN 352
On the label
  1. EN 352-1

    Type

    -1 ear defenders, -2 ear plugs, -3 helmet-mounted defenders.

  2. SNR 30

    Single Number Rating

    One average number for how much noise it cuts (dB).

  3. H 32

    High frequencies

    e.g. whine, hiss, compressed air.

  4. M 27

    Medium frequencies

    e.g. most machinery.

  5. L 20

    Low frequencies

    e.g. rumble, heavy engines.

  • Real life: HSE advises taking 4 dB off the result to allow for fit. Aim for 70-80 dB(A) at the ear. Too much protection can isolate people.
  • SNR = one average number.
  • H M L = high, medium, low pitch.
  • Take off 4 dB for real life (HSE).
  • Aim for 70-80 dB at the ear. More is not better.

Which do I need?

Noise (at the worker) Example Starting point*
85-90 dB Workshop SNR 20-25
90-95 dB Grinder, chainsaw SNR 25-30
95+ dB Breaker, jackhammer SNR 30+ or plugs + muffs (get advice)

*Starting points only. Use the HSE noise calculator or the HML method with real noise data.

Types of hearing protection

Common mistakes

  • Choosing the highest SNR. Over-protection cuts off warnings.
  • Plugs not rolled and inserted deep.
  • Glasses arms breaking the muff seal.
  • Taking them off "just for a minute". Short gaps add up.

The law

  • Control of Noise at Work Regulations 2005: 80 / 85 / 87 dB(A); peak 135 / 137 / 140 dB(C).

Shop Hearing

Ear defenders EN 352-1Earplugs EN 352-2Helmet-mounted EN 352-3

Frequently asked questions

What does SNR mean on ear defenders?

SNR is one average number. H M L are ratings for high, medium and low pitch. Take off 4 dB for real life (HSE).

At what noise level must hearing protection be worn?

At 85 dB(A) protection must be worn. At 80 dB(A) it must be offered with training. 87 dB(A) is the limit at the ear.

Is the highest SNR always best?

No. Aim for 70-80 dB at the ear. Over-protection cuts off warnings.

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