I must say, after only a short exposure to the S-92A, it is the loudest work environment I know. I have so far tried DC headset, ALPHA helmet (Stock), ALPHA Modified with Oregon Aero Hush-Kit, ALPHA Helmet Stock ear-cups with GENTEX SPH-5 Ear seals, and have now added a set of CEP. Hopefully it will help.
I'm finding that by the end of a second trip 7-8 hours, I have the ICS turned up to MAX and still have to ask for repeats. This is the loudest helo I have ever been in. Much louder than the SK or even the Chinook! I'm sure that the cockpit proximity to the MRB tips and the 4-blade design are doing it. Every bit of glass and plexi in the front office is moving like a drum skin. The windshield must be moving in and out 0.5 cm with the passage of each blade (Roughly 16 Hz). It is an astounding acoustic assault. As I recall from my HFE (Human Factors In Engineering), the danger range for Whole Body Vibrations is in the 1-80 Hz range. That puts the S-92 Cockpit environment in the first quarter (linear) or middle of that range (logarithmically). I suspect that the sound pressure levels and acceleration limits are at or above the OSH safety standards... But what can you do?