CPAP airflow with mouth closed and not inhaling

My mouth gets very dry ON. I hear airflow though I'm not inhaling. If I swallow it stops temporarily. Is this possible?

A dry mouth is often a sign of leaking. And if airflow is heard but not inhaled, it's also probably a sign of leaking. What do your Oscar / SleepHQ charts show? And what type of mask are you using?

All CPAP masks have some sort of vent built in. Air escapes the vent, and it makes a bit of noise while it's at it.

CPAP's are CONTINUOUS positive pressure devices. Even when you are exhaling, there is still some airflow creating pressure to keep your airway open. The pressure never goes to zero. And some CPAP machines send a noticeable puff of air if you are not inhaling after a certain number of seconds to test to see if your airway is open.

If you are good at keeping your lips sealed but still experiencing a very dry mouth, it may be that you are not sealing off your mouth from the airway with the back of your tongue. Did you ever play at talking under water when you were a kid? You could keep the water from going into your lungs while still opening your mouth and letting it fill with water. That's because the back of your tongue can seal off the airway from the mouth. Ordinarily someone who can't seal off the airway will have their cheeks puff out, You may be swallowing the air that accumulates in your mouth (and it comes out one end or the other!)

You can test this out by putting your tongue on the roof of your mouth, pinching your nose shut, and opening your mouth. Now can you inhale? If no air can get in, that means you are sealing off the airway, but if you can breathe in with your tongue in that position and your nose plugged, you are not sealing off the airway. You may need a Full faced mask and you may experience a dryer mouth. The humidifier can only help so much.