Sorry to say that I never really got used to the noise...but gave up trying after a couple of weeks. "White noise", unless quite loud, doesn't bother me...however the changing pitch of the machine with every breath did. Initial machine was a RemStar Plus...now have an M-series APAP. My use of a 3 setting on the C-Flex (now AFLEX) didn't help in the matter.
My solution was to mask that changing pitch with "white noise". The APAP sits just below the level of the bed...just above it on a shelf I have a Holmes air purifier. Although the Holmes has 3 fan levels, in my case the low or "quiet" setting is all it takes to do a perfect job of muting the machine noise.
