EN
ZHEN 352-2:2002
Hearing protectors. General requirements Part 2: Ear-plugs
Sizing and adjustability
The sizing and adjustability of ear-plugs is assessed to ensure that the product is suitable for the range of ear sizes designated by the manufacturer. This test is conducted using a sizing gauge or a size test fixture, which allows the confirmation that the product can provide an adequate fit for the intended consumer. Custom moulded ear-plugs are not subjected to this test.
Materials and construction
It must be ensured that the materials used in the manufacture of the device, which will come into contact with the skin, are non-staining and not likely to cause skin irritation, allergic reaction or any other adverse effect on health. The materials and construction assessment also confirms that the device is free from sharp edges, safe for use and that the cleaning and disinfection methods specified cause no damage or impairment to the hearing protection.
Resistance to damage when dropped
Resistance to damage is evaluated by dropping the hearing protection from a specified height onto a solid steel plate. If any part of the sample tested cracks or breaks then the device will fail the test. For devices which are designed for use in colder environments, this testing can also optionally be conducted at -20°C.
Cleaning and disinfection
If re-useable ear-plugs are under test, the method of cleaning and disinfection specified by the manufacturer is assessed to ensure that it causes no significant alteration to the acoustic performance of the device or to the initial properties assessed during the materials and construction properties test.
Ignitability
A steel rod heated to around 650°C is applied to the 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 subjective attenuation testing actually uses human subjects to assess the performance of a hearing protection device, and does carry a minimum attenuation value to pass the test. The results of these tests are the ones which will be published for the model when it is placed on sale and will be supplied to wearers. This test measures the threshold of hearing, 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.
Marking
Marking of the device is then inspected. This is an examination of the final product to ensure that the correct markings are present, as specified in the relevant European Standard.
Information supplied by the manufacturer
The information provided to wearers is then examined. This involves a review of the supplied user manuals to ensure that the required information is supplied to users, as specified in the relevant European Standard.