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Noise Cancelling – Hearing Protection

Noise in the workplace and at home:

Exposure to noise whether at home or at work can cause permanent, irreversible damage to your hearing. Noise induced hearing loss can be costly to the employer and be painful and stressful to the individual. Our products are designed to reduce this. When selecting the right hearing protector or headset, it is of paramount importance to select a product that is comfortable and gives the correct protection. Comfort will ensure the user wears it all the time. If you remove the hearing protector headset whilst exposed to harmful noise, adequate protection can no longer be guaranteed.
Exposure to noise at work:

  • The first action level’ means a daily personal noise exposure of 85dB(A). In this situation hearing protection should be offered.
  • The second action level’ means a daily personal noise exposure of 90dB(A). In these situations hearing protection must be worn.
  • The peak action level’ a peak sound pressure level of 140 dB(C) equivalent. A situation where, for example, a gun may be fired, hearing protection must be worn.

Assessing the protection of a hearing protector headset.
Each hearing protector headset is tested to see what its attenuation values are at specific frequencies.
The chart below is a typical example:
Attenuation Values
Headband Version
Tested and approved according to EN 352-1
Attenuation values according to EN 24869-1

Frequency (Hz) 63 125 250 500 1000 2000 4000 8000
Mean Value (dB) 12.6 14.3 19.8 25.5 30.9 34.1 36.0 36.9
Standard deviation (dB) 5.1 2.8 2.5 2.5 2.0 2.8 2.8 4.2
APV (dB) 7.5 11.5 17.3 23.0 28.9 31.3 33.3 32.7

H = 32dB M = 26dB L = 18dB SNR = 28dB
Users requiring hearing protection will normally have had an Octave-band noise assessment done. This assessment will provide a breakdown of the noise levels, at all the relevant frequencies, for specific environments (see example 1). These are normally assessed for an 8-hour exposure to the harmful noise.

Example 1:

Drilling shop:

Frequency (Hz) 63 125 250 500 1000 2000 4000 8000
Noise level dB (A) 89.0 88.6 92.0 91.5 99.5 100.0 101.5 97.0

You need to select the relevant attenuation data for the hearing protector headset you propose, and then compare the APV (Assumed Protection Value) data for the corresponding frequencies. Subtract the APV from the relevant noise level and this gives you the noise level that the user will be exposed to when they are wearing that hearing protector headset (see example 2).

Example 2:

Frequency (Hz) 63 125 250 500 1000 2000 4000 8000
Noise level in drilling shop 89.9 88.6 92.0 91.5 99.5 100.0 101.5 97.0
APV (dB) of headset 7.5 11.5 17.3 23.0 28.9 31.3 33.3 32.7
Subtract APV from Noise level 81.5 77.1 74.7 68.5 70.6 68.7 68.2 64.3

As the first action level is 85 dB (A), in order for the headset to be suitable the final figure should be BELOW 85.
Exposure time to the harmful noise is important to clarify!
Tests and Approvals.
As part of European legislation, every hearing protector headset has to be tested and approved to the relevant European standards, such as EN-352-1 and sometimes EMC directives (those with electronics). All SORDIN hearing protector headsets comply with the relevant standards associated for each product.

Useful Terminology

  • A-weighting – Weighting of the audible frequencies designed to reflect the response of the human ear to noise. The ear is more sensitive to noise at frequencies in the middle of the audible range than it is to either very high or very low frequencies. Noise measurements are often A-weighted (using a dedicated filter) to compensate for the sensitivity of the ear.
  • Active noise reduction (ANR) – The reduction or cancellation of one sound by the introduction of a second sound having equal amplitude, but with a reversed phase.
  • Attenuation – Noise reduction, measured in decibels.
  • C-weighting – Weighting of the audible frequencies often used for measurement of the peak sound pressure level.
  • Impulsive noise – Any type of single or repeated noise of short duration, e.g. the noise from a gun or printing press. Level dependent Hearing protectors designed to protect against hazardous noise while permitting good communication during quiet periods.
  • Noise exposure – A measurement of the total sound energy a person is exposed to. It is dependent on both the sound pressure level to which the person is exposed and the time over which the exposure occurs.
  • Sound pressure level (SPL) – The basic measure of noise loudness, expressed in decibels, usually measured with an appropriate frequency weighting (e.g. the A-weighted SPL in dB (A)).
  • SNR – (Single Number Rating) Is a method of estimating the attenuation of a hearing protector based on a single parameter given by the hearing protector manufacturer.

Click here for a selection of Sordin Noise Cancelling Headsets for all applications.
N.B. The Max range of accessories are designed to fit most of the leading manufacturers two way radios, should there be a problem with compatibility we will notify you immediately your order is received by our sales team.

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