Hearing protection is provided in order to prevent noise induced hearing loss which can result from the prolonged exposure to high levels of noise. Any area where the exposure to noise is at or above the noise-limit rating, which is the value of the 8 hour rating level – 85 decibels (dB) or over is considered a noise zone.
Earplugs are small inserts that fit into the ear canal. In order for them to be effective, they need to block the ear canal with an airtight seal. There are a variety of earplugs and they are available in different shapes and sizes. You can get the preformed earplugs such as the Perfect Fit Reusable Corded Earplugs or disposable foam earplugs such as Howard Leight Bilsom Earplugs.
Earmuffs fit over the entire outer ear and form a seal so that the entire circumference of the ear canal is blocked. These are held in place by an adjustable head band. The standard earmuff is not suitable in all applications. For example when head gear is required, such as a hard hat. However you can obtain hard hats which have the built in ear muffs and will then provide better hearing protection when compared to using a standard hard hat with preformed earplugs. Earmuffs are more hygienic than earplugs and can be used multiple times.
Properly fitted earplugs or earmuffs can reduce noise between 15 and 30db and are both roughly equal in sound reduction however earplugs are better suited for low frequency noise and earmuffs for higher frequency noise. Earplugs and earmuffs may be used together and this should be considered when noise exceeds 105db.
Earplugs and earmuffs have an SNR which tells you if the equipment is suitable for use in the noise zone. SNR is the Single Number Rating which is the specification used to determine the levels of protection provided by the hearing protection. However this is a European standard and one would need to look at SANS 1451 to see what is required by South African Law. In the European standard, the main function of hearing protection is to bring the noise level below the rated 85db but also not to lower the noise below 70db as this could be potentially dangerous in the worker not hearing a warning signal for example; a fire alarm, forklift reversing etc.
The higher the SNR level of the hearing protection, the more protection the user is provided. The SNR is not the amount by which the noise is reduced but rather the protection that is provided in order to bring the noise level to below the noise zone of 85db. For example; if you are working with a chainsaw where the db reading is 100db, then you require a SNR level of 28 in order to bring the noise level below that of 85db (These figures are found on the Uvex hearing protection Wheel).
When choosing the appropriate hearing protection, the following needs to be done:
- The 8 hour db rating needs to be known in order to spec the correct hearing protection.
- The working environment needs to be assessed to ensure that the hearing protection provides adequate protection and is conducive to the work that is being carried out. For example, in humid conditions a foam earplug may feel more comfortable than an earmuff providing that it meets the required SNR.
Article prepared and written by Zandy van der Westhuizen – 28.08.2020