A few weeks ago my mask started making a whistling sound. I needed to either readjust the mask or move the hose a bit and the sound went away. Not last night. No matter what I did the whistle was there. My hubby told me it was an air leak. I switched hoses and the whistling continued. I ended up sleeping with my old FFM and it felt huge and heavy. It also leaked a lot. But it didn't whistle.
So now I'm on the hunt for a new mask. I can't believe this has happened after 7-8 months of use.