My opinion on ANR, having retrofitted aftermarket to an Alpha and having it standard on a Gallet is this.
Unless your helmet is being paid for by your company, forget it.
Neither of my ANR systems has worked for more than a month before breaking down. When they were working the expense of fitting a new 9volt battery every work day was seriouslygalling. Now I use foam earplugs. They do twice as good a job as ANR and are so cheap that the cost of a bulk box from time to time is stuff all.
Try a few different types of plugs to see which is most comfortable. Personally I like the 'classic'. Its made of a medium density cylindrical foam, not tapered, not soft and squishy. For some reason these are the most comfortable for me. You may feel a bit of pressure in the inner ear to begin with but after 3 or 4 days you'll forget they're even there. When I'm finished with them I slip them into a zip pocket in my flight suit and they get cleaned when the suit goes trough the wash.
If, like me you are a slave to new technology, you'll buy the ANR anyway. Somebody gave me this exact same advice also.
Beetlenut hey!? Where abouts in PNG?