Choosing Hearing Protection: SNR Value and Fit

Choosing hearing protection starts with measurement

Handing out "maximum protection" earplugs to everyone working in a weaving hall seems at first glance like a safe decision. Yet choosing hearing protection is not a race but a matching exercise: the protector's attenuation must match the noise level of the environment.

The Regulation on the Protection of Employees from Noise-Related Risks defines three values:

Two details directly affect selection. First, when applying the action values, the effect of hearing protectors is not taken into account; for the limit value, it is. In other words, 87 dB(A) is the value the sound reaching the ear must not exceed. Second, Art. 9 of the regulation requires hearing protectors to be selected so as to eliminate or minimise the risk to hearing. This selection cannot be made without a noise measurement by an accredited laboratory; we plan measurements with accredited laboratories. For details of the values, see our article on the noise regulation, and for how measurement is carried out, our article on workplace noise measurement.

Remember: hearing protection is the last step in the hierarchy of controls. First check whether noise can be reduced at source; for methods, read our article on reducing noise at source.

What is the SNR value?

SNR (single number rating) is a single number, determined by laboratory tests, showing by how many decibels on average a hearing protector reduces sound. It is printed on the packaging and in the instructions for use; separate H, M and L values for high, medium and low frequencies are usually given alongside it. Earplugs are tested to EN 352-2 and earmuffs to EN 352-1, and they bear the CE mark.

Bear in mind that SNR is measured in the laboratory with a correctly fitted product. Protection on site is usually lower: earplugs are not inserted deeply enough, earmuff seals do not sit fully because of glasses arms or hair. The UK's OHS authority, HSE, recommends deducting 4 dB from the calculated protection to account for this difference.

Calculating the sound reaching the ear with SNR

The most practical method is this: subtract the SNR from the C-weighted equivalent noise level in the measurement report, then add 4 dB to the result as a real-world allowance. According to HSE's recommendation, the target range is for the sound reaching the ear to fall below 85 dB(A), but not below 70 dB(A).

Example: Suppose the measurement report for a weaving hall gives a daily exposure of 94 dB(A) and a C-weighted level of 97 dB(C).

If the measurement report gives only the A-weighted value, HSE's rough matching table can provide guidance:

This table can be misleading for noise dominated by a low-frequency component (such as compressors and large fans); in this case, the calculation should be made with the C-weighted measurement or the H, M and L values. At the next measurement, ask the laboratory to report the C-weighted value as well.

Why is overprotection a problem?

Overprotection means reducing the sound reaching the ear more than necessary, and it causes three problems:

1. Warning signals are not heard. A forklift horn, machine alarm or fire alarm goes unnoticed. Art. 7 of the noise regulation also requires the interaction between noise and warning signals and other sounds to be taken into account in the risk assessment.
2. Communication breaks down. The employee removes the protector to talk to a colleague and often does not put it back.
3. A feeling of isolation leads to the protector not being used.

The effect of removing the protector for a short time is greater than people think. In a 94 dB(A) environment, with a protector providing 30 dB of attenuation, the daily average reaching the ear is 64 dB(A). If the protector is removed for only 15 minutes of an 8-hour shift, the average rises to about 79 dB(A); for 30 minutes, to 82 dB(A); for 1 hour, to 85 dB(A). A comfortable protector that stays on throughout the shift is more effective than one with higher protection on paper that is frequently removed.

Earplugs or earmuffs?

There is no single right answer to the question earplugs or earmuffs; the decision depends on the working conditions, and where possible employees are offered a choice.

In hot and humid weaving halls, employees often prefer earplugs; in sections with frequent coming and going, earmuffs may be practical. In very high noise, dual protection using earplugs and earmuffs together may be considered; in this case, the SNR values of the two products are not added together, and the protection they provide together must be assessed separately. Such a need is also a strong sign that noise should first be reduced at source. For general PPE selection principles, see our article on how to select PPE.

Fitting earplugs: an earplug that is not fitted correctly does not protect

For foam earplugs, fitting earplugs is done in three movements:

1. Roll. With clean hands, roll the earplug into a thin, crease-free cylinder.
2. Pull. Pass your other hand behind your head and pull the outer ear up and back; this straightens the ear canal.
3. Hold. Insert the earplug into the canal and hold it with your finger for a while until it fills the canal.

Most of a correctly fitted earplug stays inside the canal; an earplug that sticks out of the ear when viewed from the front is usually not deep enough. A simple check: in a noisy environment, cup your palms over your ears and then open them; if the sound changes noticeably, the earplug is not sealing well. With earmuffs, make sure hair, caps and glasses arms are not trapped under the seal and that the seals are not cracked. Demonstrating fitting technique in induction training and checking it during site walks ensures the protectors handed out actually work.

Implementation in the weaving hall and health surveillance

In textile businesses, weaving and spinning halls are usually the noisiest sections. In sections exceeding 85 dB(A), the regulation requires two things together: the employer ensures and supervises the use of hearing protection and also has hearing tests carried out. Hearing tests may also be carried out in sections exceeding 80 dB(A).

Apply this on site as follows:

• Put hearing protection signs at section entrances and share the measurement result with the section supervisor.
• Record the issue of protectors in issue records and keep spare earplugs accessible in the section.
• Track hearing test and remeasurement dates with the OHS calendar tool.
• Compare hearing test results over the years; if a shift begins in an employee, reassess the choice and use of the protector. For interpreting audiometry results, see our article on audiometry and hearing tests, and for the occupational disease aspect, our article on noise-induced hearing loss.

The mistakes commonly found on site are also clear: handing out one type of earplug with the highest SNR to everyone, never demonstrating fitting technique, disposable earplugs inserted again and again with dirty hands, earmuffs with cracked seals not being replaced, and protectors removed to talk never being put back. Checking these five points on site walks ensures that the calculation in the measurement report holds true on site.

For other risks in weaving businesses, our article on OHS in weaving mills and our textile sector page will guide you. In textile businesses in Bursa and neighbouring provinces, we handle protector selection through our OHS specialist service and follow up hearing tests through our health surveillance service.

Frequently Asked Questions

What is the SNR value?

SNR is a single-number attenuation value showing by how many decibels on average a hearing protector reduces sound. It is determined by laboratory tests and printed on the packaging. Because protection on site is usually lower, an allowance of 4 dB in the calculation is recommended.

Is the hearing protector with the highest SNR the best?

No. A protector that brings the sound reaching the ear below 70 dB(A) provides overprotection; warning signals and speech cannot be heard, and the employee starts removing the protector. Selection is made according to the measured noise level.

Do earplugs or earmuffs protect better?

Both can provide adequate protection when chosen and used correctly. Earplugs are more comfortable in hot environments but require training in correct fitting; earmuffs are easy to put on and can be supervised from a distance, but there can be seal problems with glasses.

How often are earplugs replaced?

Disposable foam earplugs are renewed when they get dirty, lose their shape and according to the manufacturer's instructions; an earplug inserted repeatedly with dirty hands undermines both protection and hygiene. Washable earplugs and earmuff seals are also replaced as they wear or crack.

Is hearing protection mandatory in a section below 85 dB(A)?

For exposure above 80 dB(A), the employer makes hearing protectors available to employees. The threshold at which use is mandatory and supervised by the employer is 85 dB(A).