Hearing Protection

It is extremely important to protect your hearing. Once damaged, it does not come back. So if you work in a noisy environment, you must use some form of hearing protection.

 

Content:

When?

You risk damaging your hearing at noise levels above about 80 dB(A). The risk rapidly increases at higher noise levels. The likely risk of damaged hearing from an eight-hour working day over a period of ten years is as follows:
 

80 dB(A)

0% risk
85 dB(A)4% risk
90 dB(A)11% risk
95 dB(A)24% risk   

How long?

The risk of hearing damage depends largely on the time you are exposed to noise. Even very brief exposure to high noise levels can cause damage. So it is vital that you always use hearing protection. For example, the following combinations of noise level and exposure times will give the same noise impact:
 

85 dB(A)8 hourse.g. working in a workshop all day
91 dB(A)2 hourse.g. cleaning in a separator room
97 dB(A)30 minutese.g. working close to a fan
102 dB(A)10 minutese.g. inspection in the engine room
112 dB(A)1 minutee.g. near turbochargers



    


    

 

What types?

There are many different types and makes of hearing protection. You will find the most important below:


Ear plugs
Small plugs made out of foam or cotton wool inserted into the ear canal. They are available with a cord or strap. The advantages are good noise reduction, very light weight, free air circulation around the ear and they are not easy to lose. The disadvantages are that they can irritate the skin in the ear canal. Also noise reduction depends on correct insertion into the ear canal and they are not suitable for repeated removal/re-insertion.


Personal custom fit earplugs
Type of ear plug moulded in silicone to an impression of the individual's ear canal. Available with filter (small opening) that is adjustable to the user's requirements for different levels of noise reduction and frequency range.
The advantages are that they provide a good fit and that they eliminate pressure on the eardrum by means of pressure equalisation through the small opening.

 

Ear cups
The most common type of hearing protection, they consist of a set of plastic ear cups with sound-absorbent material. They fit the ear snugly. The advantages are good noise reduction at high and low frequencies, they can be fitted with radio/coms equipment and they are easy to put on and take off. If this type of ear protection is used with radio/communication equipment, the sound level of the signal inside the cup is limited to about 85 dB to prevent users from turning up the volume too much. The disadvantages are that the cups can make the ears sweat in hot conditions, they can fall off and that they are comparatively bulky and heavy.

 

Electronic hearing protection
A type of ear cup where noise reduction only occurs at the high noise levels where it is needed. Electronically enhanced listening ensures that low noise levels are boosted while high noise levels are reduced as in ordinary ear cups. This is ideal in areas with varying sound pressure and impulse noise. The disadvantage is the heavy weight of the electronics and batteries.


Active Noise Reduction ear cup
The most advanced type of ear cup protection. Noise is reduced by electronically transmitting antiphase noise into the cup. This provides particularly good noise reduction in addition to the passive reduction of the cup itself. The disadvantages are that ANR only works at low frequencies, the electronics make the cup heavy and bulky and finally, they can damage hearing if the electronics fail.

How great is the reduction?

The reduction levels for hearing protection are described in catalogues and data sheets as HML standards (high, medium and low frequency reduction).

Choosing the right protection

There are three things to consider when choosing hearing protection. Protection must provide sufficient noise reduction but not more than necessary to allow communication with others and to hear alarms. This depends on the type of noise you are exposed to and the kind of work you are doing. Finally, it is extremely important to wear hearing protection all the time you are working so it should be as comfortable as possible. Protection should reduce the noise entering the ear to 75 - 80 dB(A). In special cases, consider using a noise meter to help you choose the right type of protection. Below you can see some examples that illustrate typical situations and choice of protection.
 

Extended duties in the main engine room
The noise here is constant and loud at high and low frequencies. So it is a good idea to choose protection with good all-round characteristics, such as ear plugs or good quality ear cups where the ears do not become too hot.

 

Working in the funnel close to the exhaust
The noise here is dominated by a strong low frequency noise from the exhaust from the diesel engines. Good noise reduction at low frequencies requires a large robust cup, such as the Bilsom Viking, Peltor H10A or else good ear plugs. In such cases, ANR ear protection would also be effective as it provides particularly good reduction at low frequencies.

 

Rust scaling
Noise is dominated by short very loud pulses so ANR electronic ear protection would be suitable since it would be possible to hear better in quiet periods.

 

Loading/unloading on the car deck
The noise here is extremely variable with only brief periods of high noise levels. At the same time, it is necessary to be able to communicate. ANR protection would also be appropriate in this situation.

 

Short-term inspection in a ferry steering gear room
The noise here can be particularly loud, sometimes over 120 dB(A) and at high frequencies. Here a combination of ear plugs and ear cups is recommended. This is partly to get a high level of noise reduction and partly to ensure protection if the cups fall off or are briefly lifted when working.
 

Health and Safety Consultant
Master Mariner, M.Sc. Maritime Affairs

Vivek Menon

vm@seahealth.dk

+45 3311 1833
+45 2960 7427