Attendance at hearing tests at work
This falls into two categories, employers arranging tests and then employees refusing to attend, or employers arranging audiometry sessions but then telling employees attendance is voluntary.
Employee refusal to attend
This is nice and clear, employees cannot refuse to attend a hearing test provided by their employer as part of their duties under the Noise Regs, as long as the test is taking place in the employees' normal working hours and it is being provided because the employee works in a noisy area. Attendance is not optional. This is specifically stated in the Noise Regs, covering it in the regulation itself rather than merely in guidance. This is in Regulation 9 of the Noise Regs. If someone refuses then treat it within the disciplinary procedure as any other non-compliance.
For employees who are found to be at risk, follow-up action may be necessary, for example by talking to their line manager about possibly swapping them to a quieter job, or providing different stronger hearing protection, or that time off may be needed for follow up visits to a specialist to examine any issues further. In all these cases the person responsible for the audiometry programme should sit down with the employee and get their consent for that. I've never come across people refuse that when it is explained properly as it is for their own benefit.
Employers making attendance optional
For employers, if they have a workplace noise level which is sufficient to trigger the audiometric testing requirements of the Noise Regs then they cannot then allow employees in high noise areas to choose to attend or not - this is very naughty. Spanky spanky. It is not sufficient for the employer to merely make appointments available and then leave it up to the employees as to whether they attend or not.
If people are included in the audiometry programme who do not work in high noise areas then it is perfectly OK for their attendance to be optional.
For full disclosure - we provide audiometry services but as we charge per appointment rather than per test, it makes no difference to us if someone attends for a test or not as we charge for that appointment either way, so we have no vested interest in any of the above.