Understanding EN 352 - Hearing protection standard

 

Millions of employees across the world are exposed to excessive levels of noise in their workplace. Because of this, many suffer work-related hearing loss, tinnitus and other related medical conditions, which may have a permanent effect on their quality of life.

 

With serious health implications at stake, employers should be placing an emphasis on providing their employees with the correct hearing protection. The Control of Noise at Work Regulations 2005, which replaced the Noise at Work Regulations 1989, came into force in Great Britain in 2006. Its aim is to ensure that all workers’ hearing is protected from excessive noise at their place of work.

 

To ensure the hearing protection you provide is fit-for-purpose and in line with the requirements of The Control of Noise at Work Regulations 2005, ear protection products for sale in Europe must meet the EN352 series of European standards.

 

In this guide we will be covering the basic requirements of EN 352, as outlined in parts 1 to 3.

 

 

When is hearing protection needed?

According to The Control of Noise at Work Regulations 2005, the exposure level at which employers need to provide hearing protection is a daily or weekly personal noise exposure of 85 dB (decibels). Those who are working in noise levels between 80 dB (lower action level) and 85 dB must be provided with suitable hearing protection on request. Where noise levels reach or exceed 85 dB (upper action level), suitable hearing protection must be supplied and worn.

 

The exposure limit is 87 dB; this figure takes into account any reduction in exposure provided by hearing protection. Workers must not be exposed to noise levels exceeding 87 dB, whether they are wearing ear protection or not.

 

Hearing protection should be chosen when extra protection is needed above what can be achieved with noise control. It can also be used as a short-term measure while other methods of controlling noise are being put in place.

 

 

EN 352 standards explained

The first 3 parts of EN352 cover the basic requirements of hearing protection and define the passive performance requirements. This includes the requirements for size, materials and construction.

 

The instructions for EN 352 testing methods are not included within these 3 basic parts, instead they refer to another standard, EN 13819. EN 13819 details the testing methods common to all types of hearing protectors covered by EN 352, and come in 2 parts: 1) Physical test methods and 2) Acoustic test methods.

 

Another standard mentioned in EN 352 is EN 458, which covers selection, use, care and maintenance of hearing protectors.

 

To meet the EN352 standards, hearing protection is tested in the following areas (subject to product type):

  • Materials and construction

  • Sizing and adjustability

  • Cup rotation

  • Headband force

  • Cushion pressure

  • Resistance to damage when dropped

  • Change in headband force

  • Resistance to leakage

  • Ignitability

  • Minimum attenuation

  • Marking

  • Information supplied by the manufacturer

 

 

EN 352-1:2002 - Hearing protectors - Ear muffs

Ear muffs tested in accordance with EN 352-1:2002 must be labelled with the standard number, manufacturer and model identification. Where required, there should also be indication for the orientation of the ear muff e.g. ‘TOP’ and/or ‘LEFT’ and ‘RIGHT’.

 

Materials and construction

Any materials used to make the product that will come into contact with the skin must be non-staining and not likely to cause skin irritation, allergic reaction or other adverse effects on health. The device must be free from sharp edges to be considered safe for use, and cleaning and disinfection methods specified should not cause damage or impairment to the hearing protection.  

 

Size and adjustability

This is tested to ensure that ear defenders are suitable for the range of head sizes designated by the manufacturer. With EN 352-1:2002 compliant products you should expect an adequate fit.

 

Cup rotation

Hearing protectors are measured to assess whether or not the rotation of the cups is sufficient. There must be enough rotation for wearers to adjust the device to achieve the best fit.

 

Headband force

There should be no excessive force on the wearer’s head.

 

Cushion pressure

There should be no excessive pressure on the wearer’s head.

 

Resistance to damage when dropped

For this test, the ear protection product is dropped from a specified height onto a solid steel plate. If part of the product cracks or breaks then it will fail the test.

 

Change in headband force

After the tests above have been completed, headbands are subjected to flexing for 1000 cycles, before being conditioned in a water bath at 50°C for 24 hours. Once complete the headband force is measured a second time. A maximum deviation between the 2 measurements determines whether it passes.

 

Resistance to leakage

This is specifically for ear muffs with fluid-filled cushions. A vertical load of 28±1 Newtons is applied to the cushion for 15 minutes and any leakage caused will constitute a test failure.

 

Ignitability

A steel rod heated to around 650°C is applied to the hearing protection device. If any part ignites or continues to glow after the removal of the rod then the device will fail the ignition test.

 

Minimum attenuation

The minimum attenuation value must be recorded for EN 352-1 compliant ear muffs. This is the lowest sound pressure level perceivable by the ear of 16 human test subjects with and without the hearing protection worn. It is then possible to calculate the performance of the model from these values.

 

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EN 352-2:2002 - Hearing protectors - Ear plugs

The second section of the EN352 standards, EN 352-2:2002, specifies the constructional, design, performance and marking requirements for EN 352 compliant ear plugs. This includes specification for the sound attenuation of the ear plugs, measured in accordance with EN 24869-1.

 

Ergonomic aspects of the ear plugs are addressed by taking into account the interaction between the wearer, device and, where possible, the working environment in which the device is likely to be used.

 

The markings for EN 352-2 may only appear on the packaging; these include the standard number, manufacturer and model identification. In addition to these markings the packaging for EN 352-2 ear plugs should also state whether they are disposable or reusable, have fitting instructions, include the nominal size of formable plugs (ranging from 5-14mm), and custom moulded ear plugs should have LEFT/RIGHT differentiation.

 

Ear plugs are tested for many of the properties outlined above in EN 352-1:

  • Sizing and adjustability

  • Materials and construction

  • Resistance to damage when dropped

  • Ignitability

  • Minimum attenuation

 

There are, however, some small differences to testing methods in EN 352-2. Custom moulded ear plugs are not tested for sizing and adjustability, and with reusable ear plugs, the method of cleaning and disinfection specified is assessed to ensure it causes no significant alteration to the acoustic performance or to the material and construction properties.  

 

 

EN 352-3:2002 - Hearing protectors - Ear muffs attached to a safety helmet

The third section deals with the specific requirements for ear muffs attached to industrial safety helmets. In EN 352-3 products are tested for all properties mentioned in the EN 352-1 section, as well as specific testing methods for helmet mounted ear defenders.

 

The markings to be included on EN 352-3 ear muffs are the standard number, manufacturer and model identification, as well as indication of orientation where required e.g. ‘TOP’ and/or ‘LEFT’ and ‘RIGHT’.

  

 

EN 352 Parts 4 to 8

From part 4 onwards, the EN352 series deals with the safety requirements and testing methods for additional functions built into hearing protectors. An example of this is a ‘level dependent’ function, covered in EN 352-7. Level dependent ear plugs are designed to provide restoration of external sounds, while also providing attenuation of sound at high sound pressure levels. Other additional functions include active noise reduction and audio communications.

 

You can see the full list of additional hearing protection functions covered by EN 352 below:

 

EN 352-4:2001 - Hearing protectors - Level dependent ear muffs (Amended 2006)

 

EN 352-5:2002 - Hearing protectors - Active noise reduction ear muffs (Amended 2006)

 

EN 352-6:2002 - Hearing protectors - Ear muffs with electrical audio input

 

EN 352-7:2002 - Hearing protectors - Level dependent ear plugs

 

EN 352-8:2008 - Hearing protectors - Entertainment audio ear muffs

 

 

How to choose hearing protection

When you are looking for fit-for-purpose ear protection, look out for the EN 352 markings. EN 352 certification will ensure they have been tested in accordance with European standards, and therefore possess all of the properties required for effective and reliable hearing protection.

 

Before a decision is made, however, you will need to work out the particular employee’s daily or weekly noise exposure, measuring the noise level of each task they are required to carry out and how much time is spent on the task. This can be done with a professional decibel meter (sound level meter)

 

The noise levels recorded can then be entered into a noise exposure calculator. Once you’ve calculated the employee’s daily or weekly noise exposure, you then need to work out what Single Number Rating (SNR) is required to maintain compliance with The Control of Noise at Work Regulations 2005.

 

Every hearing protection product will come with an SNR, and this allows you to compare the protection offered by different products in order for you to make the best decision. The higher the SNR level, the more protection the product gives.

 

Here are the SNRs required to remain compliant at various noise levels:

Noise Level

Minimum SNR

Ideal SNR

Maximum SNR

85 dB

5

9 – 14

18

90 dB

10

14 – 19

23

95 dB

15

19 – 24

28

100 dB

20

24 – 29

33

105 dB

25

29 – 34

38

110 dB

30

34 – 39

43

 

Ideally, you are looking for hearing protection that will reduce noise exposure to between 75-80 dB. Any product that reduces it below 70 dB is considered ‘overprotection’ according to BS EN 458:2016.

As an example, the JSP Monaco headband ear defenders conform to EN 352-1 and have an SNR of 36 dB which makes them ideal for workplaces with a high noise level of 110 dB. The JSP Soundstopper banded earplugs conform to EN 352-2 and have an SNR of 21 dB which makes them ideal for workplaces with a noise level of 95 dB.

 

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Author

Glen Smith

Having worked at WISE Worksafe for over 15 years, Glen Smith our Marketing Manager has a wealth of experience in corporate branding and company clothing. He has a passion for making brands stand out from the crowd, and coming up with innovative solutions to support our clients in this process.