You must provide health surveillance (hearing checks) for all your employees who are likely to be regularly exposed above the upper exposure action values, or are at risk for any reason, eg they already suffer from hearing loss or are particularly sensitive to damage.
The purpose of health surveillance is to:
Consult your trade union safety representative, or employee representative and the employees concerned before introducing health surveillance. It is important that your employees understand that the aim of health surveillance is to protect their hearing. You will need their understanding and co-operation if health surveillance is to be effective.