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?
The thing is that it needs to be literally perfect polarization flipping to protect you. ANC as we know isn’t perfect; it doesn’t perfectly cancel sound and create absolute silence. You’re still potentially vulnerable to high SPL