If I recall correctly the maximum Noise Reduction Rating (NRR) for earplugs and earmuffs is around 30db. You can combine the two for a slight increase in hearing protection but you still hit a limit because of bone vibration.
Is there PPE out there to go even further beyond this? Where would it be commonly used?
Except that’s exactly how nose canceling ear phones work. It’s not like they have an external speaker projecting sound 🤦🏼♂️