weird noise in mask

I have been using my resmed 10 for about 9 months now with varying results.
However last night had me really stumped
I was getting a really strange noise which seemed to be coming from my mask. It sounded like a loud clunky noise which happened each time I breathed in. I checked everything and by about 2am, I was so tired I had to take it off. The problem with that is that I couldn't go to sleep without it!
So I put it back on and just tried real hard to put up with it. It did seem to get less as time went on and wasn't there this morning.
I use a nasal mask with a chin strap.
Any ideas what this could be?

I had what sounds like the same sort of thing while in intense REM sleep: the valve was clunking back and forth as I was breathing very heavily, and it woke me up it was so loud!

It could be rainout, water in the tube.

Search rainout on these forums for causes and solutions.

Are you using a humidifier?

Sheriff