EAP86
(and current ANR systems don't reduce the noise energy by very much at all)
EAP, I don't doubt your experience of this, but I'd ask what systems are being used and who did the noise surveys for each application.
I recall that in the mid-90s there was little or no understanding that it wasn't a case of using any old broadband ANR system, such as those used in the back of armoured vehicles where the occupants don't need to hear too many audio cues. Merlin, for example, didn't understand this, as they were fixated on ANR for passengers (troops), ignoring the fact that it was aircrew who were receiving the long term damaging (as distinct from annoying) noise dose. In 2012, a well-known audio company were still selling broadband systems to aircrew. And presumably telling them it was safe. MoD was 30 years ahead of them. Only MoD didn't know this, as it had lost corporate knowledge. Witness, in 2006 the Nimrod IPT issued an Invitation to Tender to develop an 85dB(A) system for aircrew, ignorant of the fact Sea King had already delivered an upgraded 75dB(A) system in 2000 (73 achieved) that actually met the legal requirement. When informed of this by one bidder, the company was blacklisted and removed from the tender list, because the IPT wouldn't admit it was about to let a multi-million development contract for something that was on its own shelf at £750. In fact, and a little sarcastically, they were offered the RN's old 85 system free of charge, if that's what they really wanted. This leads me to believe that a wheel is being reinvented.