When is hearing protection compulsory?

This is a shortened version of a full page discussing this in detail here: Hearing protection - Optional or 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. 

80 to 84dB(A) - Optional

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.

85dB(A) and over - Compulsory

Once the noise levels hit 85dB(A), then there is no choice but to wear hearing protection and it is no longer optional.

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 really hate their employees.