How to Choose Hearing Protection: SNR Ratings, Comfort, and Fit for UK Workplaces

The SNR number on an ear defender box is the most-asked-about figure in UK hearing protection — and one of the most misread. A pair of ear defenders rated SNR 33 is not "33 dB of protection" in the way most buyers assume, and picking the highest-numbered product on the shelf often produces worse compliance outcomes, not better.

This guide covers what the SNR rating actually means, how to choose hearing protection that fits the exposure profile in your workplace, and the comfort and fit issues that determine whether the protection actually gets worn.

This guide covers hearing protection selection for UK employer noise duties. It is not product endorsement and does not promote any specific brand. For complex acoustic environments or borderline exposures, get input from a competent occupational hygienist or noise consultant on the residual exposure your protection programme delivers.

What SNR rating actually means

SNR stands for Single Number Rating. It is the European standard's headline figure for the noise attenuation a hearing protector provides — measured in a laboratory under controlled conditions, with the protector fitted correctly by trained operators.

The number expresses the average attenuation across the relevant frequency range. An SNR 25 ear defender, fitted as it was in the lab, reduces the noise reaching the ear by approximately 25 dB across the test frequencies. The standard governing the test is BS EN 352, which sets out how the measurement is performed.

Two facts that consistently surprise buyers:

1. Real-world attenuation is lower than the SNR figure — often by 4-10 dB for ear defenders and more for ear plugs. The lab fit is optimal; workplace fit rarely is. HSE's L108 guidance explicitly addresses this gap and recommends derating SNR figures when assessing real-world protection.
2. More attenuation is not better — over-protection is a recognised compliance issue. Workers who cannot hear warning signals, communicate with colleagues, or detect machinery faults face different safety risks. The target is adequate attenuation, not maximum attenuation.

How SNR works in practice

The standard way to estimate the protected exposure level is:

Protected level (dB(A)) = unprotected level (dB(A)) − (SNR − 4)

The "− 4" is the conservative HSE-recommended derating to account for real-world fit and use. So a worker exposed to 95 dB(A) wearing an SNR 25 protector has an estimated protected exposure of 95 − (25 − 4) = 74 dB(A) — well below the lower action value.

That formula gives a quick check, but it is not the only method. L108 also covers the HML (high/medium/low) method and the octave-band method for situations where the noise spectrum is unusual or where SNR alone is misleading. For most SME workplaces with broadband industrial noise, the SNR-with-derating approach is fit for purpose.

How much SNR do you actually need?

The aim is to bring exposure below the upper exposure action value (85 dB(A) daily) — and ideally close to, but not below, 75 dB(A). Below 70 dB(A) is generally regarded as over-protection.

Working from typical workplace exposures:

• Workplace noise level 85-90 dB(A): SNR 20-25 is usually appropriate. Lower-rated disposable plugs (SNR 24-30) often work well; mid-range muffs (SNR 25-28) also fit.
• Workplace noise level 90-95 dB(A): SNR 25-30. Typical ear defender range or higher-rated plugs.
• Workplace noise level 95-100 dB(A): SNR 30-35, possibly dual protection (plugs + muffs combined).
• Workplace noise level above 100 dB(A): Specialist assessment needed — over-protection becomes harder to avoid and dual protection is usually required.

These figures are starting points, not formal recommendations. The protected exposure should be calculated using actual measured or estimated noise levels at the worker, not generic workshop numbers. For guidance on producing those exposure figures, see How to Complete a Noise Risk Assessment.

Why over-protection is a problem

Buying the highest-rated protection on the basis that "more is better" creates real safety issues:

• Communication breakdown — workers cannot hear instructions, leading to mistakes and the temptation to remove protection partially
• Warning signals missed — vehicle reversing alarms, machinery fault alarms, and verbal shouts cannot break through over-attenuated protection
• Isolation and fatigue — sustained over-attenuation contributes to worker fatigue and disengagement; workers stop wearing the protection because it makes the work environment feel unworkable
• The non-compliance loop — when workers feel they have to lift a defender every minute to hear a colleague, they often stop wearing it altogether

A protector that delivers 20 dB(A) of real-world attenuation reliably worn for 100% of exposure time produces a better compliance outcome than a 35 dB(A) protector worn 70% of the time. Time-in-protection compounds; missed-time exposes the wearer at the unprotected level.

Ear defenders vs ear plugs vs banded plugs

The form factor matters as much as the SNR number, because it determines whether the protection actually gets worn.

Over-the-head ear defenders (muffs):

• Strengths: quick to fit and remove, visible compliance (you can see at a glance whether they are on), more consistent fit across users, better for intermittent noise where workers move in and out of high-noise zones
• Weaknesses: uncomfortable in heat, hard to combine with hard hats unless purpose-designed (helmet-mounted versions exist), spectacles can break the seal and reduce attenuation by 5+ dB

Disposable foam ear plugs:

• Strengths: highest attenuation per unit cost, comfortable for long shifts, easy to combine with other PPE, no heat trap
• Weaknesses: fit is highly user-dependent — incorrectly inserted plugs deliver a fraction of the rated attenuation; difficult to use in dirty environments where contamination of the plug before insertion is likely; harder to verify visible compliance from a distance

Banded ear plugs:

• Strengths: quick on/off for intermittent exposure, no consumable cost, fit more consistent than disposables for trained users
• Weaknesses: lower attenuation than reusable plugs of similar form, band pressure becomes uncomfortable over long shifts

Custom-moulded plugs:

• Strengths: best long-term comfort, consistent fit by design, most accurate attenuation in real-world use
• Weaknesses: higher initial cost (typically £80-£200 per pair), need to be re-moulded if hearing changes or jaw alignment changes, lost plugs are expensive to replace

For most SME workplaces with mixed exposure profiles, a programme of ear defenders for high-noise zones plus disposable plugs for intermittent or supplementary use is more practical than a single-form-factor approach.

Comfort and fit — the determinants of compliance

Hearing protection delivers no protection when it is not being worn. The features that determine sustained compliance:

• Weight and clamp force — heavy or tightly-clamped muffs become unwearable after a few hours
• Material and warmth — gel or foam cushions degrade in heat and cold; deteriorated cushions break the seal and reduce attenuation
• Compatibility with other PPE — hard hat, safety glasses, respirator, and welding shield all interact with hearing protection. Test combinations before committing to a product family.
• Re-fittability — workers who have to remove protection to communicate must be able to refit it correctly without supervision. Plugs that need rolling and inserting through pulled-back ear are reliably misfitted on the third attempt of the shift.
• Hygiene and replacement — replaceable cushions on muffs, daily disposable plugs, or custom-moulded options that are washable. A protector that becomes uncomfortable for hygiene reasons (sweat, dust, ear discharge) gets removed and not replaced.

What the regulations require beyond the SNR number

Regulation 7 of the Control of Noise at Work Regulations 2005 requires employers to:

1. Make hearing protection available at the lower exposure action value (80 dB(A) daily)
2. Ensure hearing protection is used at the upper exposure action value (85 dB(A) daily)
3. Provide information, instruction, and training so workers know why, when, and how to wear it
4. Maintain hearing protection in efficient working order — replace damaged cushions, deteriorated foam, broken bands

The selection itself is implicitly required to be appropriate to the exposure — a defender that delivers inadequate or excessive attenuation does not meet the duty in spirit, even if the box says it is rated for noise.

The compliance trail HSE inspectors look for:

• Selection rationale — written evidence that you assessed exposure, selected protection appropriate to the level, and considered comfort/fit/compatibility issues
• Issue records — who received what, when, with size/type appropriate to the wearer
• Replacement schedule — how often consumables are replaced, how worn-out reusables are identified and replaced
• Training records — initial training plus refreshers, with evidence of fit-checking for plugs

For the broader regulatory framework that underpins these duties, see UK Noise at Work Regulations: The Complete Employer Guide. For where hearing protection sits in the broader noise control picture, see Noise Control Measures: The UK Hierarchy — protection is the residual layer, not the first response.

Frequently asked questions

What does SNR mean on ear defenders?

SNR (Single Number Rating) is the average noise attenuation a hearing protector provides under laboratory conditions, measured according to BS EN 352. It is expressed in decibels — an SNR 25 protector reduces noise by approximately 25 dB across the test frequency range when fitted correctly.

How do you calculate SNR for hearing protection?

To estimate the noise level reaching the ear when protection is worn, subtract the SNR (with HSE-recommended 4 dB derating) from the unprotected exposure: protected level = unprotected level − (SNR − 4). For a worker exposed to 95 dB(A) wearing an SNR 25 protector, the estimated protected level is 95 − 21 = 74 dB(A).

What SNR rating do I need for 90 dB exposure?

For exposure around 90 dB(A) daily, an SNR 20-25 protector is typically appropriate — bringing the protected exposure into the 70-75 dB(A) target range without over-protecting. Higher-rated protection (SNR 30+) risks over-protection, communication breakdown, and reduced compliance.

How hearing protection selection fits ongoing compliance

Selection is the easy part. The harder part is the ongoing compliance work — issue records, fit checks, replacement schedules, training, and audiometric surveillance for workers exposed at or above the upper action values. For the audiometry side of the workflow, see Workplace Audiometry: When UK Employers Need Hearing Tests. For the hearing protection zone framework that determines where mandatory protection applies, see the free Hearing Protection Zone Checklist.

Sources

• The Control of Noise at Work Regulations 2005 — legislation.gov.uk
• Regulation 7 (Hearing protection) — legislation.gov.uk
• L108: Controlling Noise at Work (3rd edition, 2021) — HSE
• Hearing protection — HSE
• Choosing the right hearing protection — RNID