The Effect of Hearing Protection
Listen to Teli Chinelis discussing how a common request from instructing solicitors in noise-induced hearing loss claims is to review the adequacy of hearing protection, and this sometimes is asked even when the Claimant does not state that they made use of hearing protection.
Studies of the “real world” attenuation of hearing protection were conducted for the Health and Safety Executive at Salford University in 1990 and at the Health and Safety Laboratory in 2009. The Salford study found that the performance of earmuffs was typically 5 dB less effective than was suggested by the manufacturer’s data. They found no significant differences between earmuffs with high and low headband pressure but observed degradation in performance of between 0.4 and 5.7 dB, associated with the wearing of spectacles.
The Health and Safety Laboratory study involved artificially ageing earmuffs by stretching the headband; they found a mean decrease in attenuation of 6 dB when compared with the manufacturer’s data.
The studies also found that the attenuation provided by earplugs is highly variable, in the worst cases providing no significant attenuation at all. This was thought to be due largely to inconsistencies in the way plugs were fitted by their users [demonstrating the importance of training in their correct use].
A review of the Salford and other studies noted that, even where earplugs are correctly seated, jaw movement is likely to move the plug over time.
Current HSE guidance on noise in the second edition of L108, advises employers that a ‘real world’ correction of -4 dB should be applied to the attenuation of hearing protection when assessing ‘protected’ exposure levels. It also advises that earplugs can work loose over time and should be refitted in a quiet environment, every hour.
In our experience, some noise-exposed workers complain that their hearing protection is inadequate because, when wearing it, they are still able to hear the noise. However, any expectation that hearing protection should eliminate external sounds completely is unrealistic and undesirable and may reflect a lack of adequate information or training.
When wearing hearing protection in a noisy environment, the individual will still hear sounds that are subjectively ‘noisy’, although at reduced levels that will usually be acceptable in respect of risk to hearing.
It is reasonable to assume that any earplug or earmuff, on the market for industrial use, is likely, if in good condition and worn fully and correctly when required, to reduce the noise level at the ear by at least 10 dB to 15 dB, and this level of attenuation is, in the majority of occupational situations, sufficient to protect against hearing damage. However, the reduction in daily exposure afforded by hearing protection is severely compromised if it is not worn for all the time necessary. For instance, if hearing protection is worn for only 50% of the time, then the protection provided by the very best hearing protection is just 3 dB.
If you would like any more information about the effect of hearing protection please contact [email protected] who will be happy to help.
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