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?
Active noise cancelling does reduce the actual sound pressure (that’s the only way volume can be reduced). See for example: https://en.wikipedia.org/wiki/Hearing_protection_device#Electronic_hearing_protection_devices.
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