Personal Hearing Protection (PHP) is often used to reduce the noise exposure of employees. It should only be considered as a last resort after alternative methods of reducing exposure have been considered.
Two main types of PHP are available: Ear muffs and Ear plugs, and each is described below:
Ear muffs cover the entire outer ear and are generally constructed from a hard outer shell that is filled with an absorbent lining. A soft cushion ensures a good fit between the muff and the side of the head.
Ear muffs may either be mounted on a headband, or can be attached to a safety helmet. It is important to ensure that the muffs are maintained in good condition and that the cushions remain intact. The headband should maintain pressure on the muffs against the side of the head.
There are a number of advantages and disadvantages to muffs.
|It is obvious when an employee is wearing them.||They can be uncomfortable.|
|They are easily removed and reapplied (eg if moving between noisy and quiet areas).||Glasses, long hair and ear jewelry can create a poor seal with the side of the head.|
|There are hygienic as they are not inserted into the ear||Expensive compared to ear plugs.|
Ear plugs are inserted into the ear canal and block the transmission of noise down the canal. They can vary from cheap disposable foam type plugs, which expand to fill the ear canal, to expensive personalised plugs.
It is very important with earplugs to ensure that they are worn correctly in order to achieve their rated performance and we recommend that employees should receive training on the correct method of insertion.
There are a number of advantages and disadvantages to plugs.
|Glasses, long hair and ear jewelry do not interfere with their performance.||They can be uncomfortable.|
|Cheap.||It is not obvious when an employee is wearing them.|
|They are not easily removed and reapplied (eg if moving between noisy and quiet areas).|
|They can be unhygienic and lead to dirt being inserted into the ear.|
|They can be difficult to insert correctly.|
It is vital to ensure that PHP is worn continuously by employees where required. Removing PHP for even a short period of time will negate the effect of the PHP and this is demonstrated in the graph. The dotted lines show the protection afforded by PHP when worn for an entire 8-hour shift, for three types of PHP giving performances of 10 dB, 20 dB and 30 dB. The solid lines show the equivalent protection achieved if the PHP is removed for a number of minutes during the shift.
In our experience, it is good practice to provide a choice of muffs and plugs to employees (provided that both can give the required attenuation) as it is vital that the PHP is worn and employees are more likely to wear something that they find to be comfortable.
Manufacturers quote the performance of PHP in terms of octave bands. This allows an employee’s exposure while wearing the PHP to be calculated and assessed. In extremely high noise environments it may be necessary to wear ear plugs and ear muffs together. It should be noted, however, that the overall performance is less than the sum of the performance plugs and muffs separately.