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?
I wonder if there would be a way to counter that though. Maybe some kind of sound-focused bomb suit developed for a single profession?
I imagine most situations are avoidable with modern technology allowing us to do things remotely but perhaps there was something used historically or as part of a “because I can” experiment.