When is hearing protection optional and when is it compulsory?
The Noise Regs contain provision for both cases, so in some areas it is optional and in others it is compulsory, with the deciding factor being the noise exposures involved.
Noise levels of 80 to 84dB(A)
If the noise assessment identifies exposures in this range, then hearing protection must be provided by the employer, employees should be told it is available, they should be informed about the dangers of excess noise, and then it is up to them if they choose to wear it or not. Usage is therefore optional.
This is covered by Regulation 7 in the Noise Regs. Technically the Regs say hearing protection is optional between the two limits of 80 and 85dB(A), and then say it is mandatory from 85dB(A) upwards. In reality, in a noise assessment a point of a decibel, (e.g. 84.3) is always rounded up or down to the nearest whole number, meaning 84.4dB(A) is rounded down to 84dB(A) so hearing protection is optional, whereas 84.5dB(A) is rounded up meaning it becomes 85dB(A) and hearing protection is mandatory, hence identifying it as 80 to 84dB(A) above as 84dB(A) is the maximum level where hearing protection use can remain optional.
Why set it at this noise level?
The theory behind this is that at 80 to about 85dB(A), a small number of people who are particularly sensitive to noise have a slight change of developing hearing loss from regular long term exposures.
Noise levels of 85dB(A) and over
Once the noise levels hit 85dB(A), then there is no choice but to wear hearing protection and it is no longer optional.
Why set it at this noise level?
The medical bit behind this is that once noise levels reach this and above, then the majority of people exposed to these noise levels regularly and for long periods will have some form of hearing damage, with that risk then increasing with increasing noise levels.
Employers enforcing hearing protection use from 80dB(A) onwards
An employer cannot do less than the Regulations but can do more and some choose to just have hearing protection set as mandatory from the 80dB(A) level upwards. This is perfectly fine in law and is a choice the employer can make if they choose.
When hearing protection is worn in quieter areas, such as 81 or 82dB(A) at the choice of the employee, or its use is mandated by the employer, the employer must ensure that the users are not over-protected. This simply means the hearing protection used is too strong for the noise risk present. Ideally, under the hearing protection the users should be somewhere in the mid-70s dB range as that is a comfortable volume which does not cause isolation issues or lead to a risk of things like alarms going unnoticed. This means therefore that strongest is usually not always best and hearing protection which has a smaller reduction on the noise levels present is needed. This is known as low attenuation protection of which there are many types on the market.
The Hearing Protection Data page on this site lets you sort the listed protectors by SNR (or HML) to identify the ones with the smaller impact on the overall noise levels.
As a side comment, even for jobs exceeding the magic 85dB(A) level, the maxim of 'strongest protector is best' still is very much a false premise and over-protection risks do still remain.
Employee disclaimers and waivers
A common question from employees is that they don't like wearing ear plugs or muffs, so can they 'just sign something' that they accept the risks and can then carry on not wearing anything. The answer to this is an unambiguous no as the employer cannot disclaim responsibilities set out in legislation and it can also be deemed an unfair contract. So no, employees cannot sign disclaimers absolving their employer for any responsibility should they suffer hearing loss down the line.