quietest mask?

I have used a nasal pillow mask, which I find most comfortable, but my mouth opens while I sleep, causing air to flow out noisily. I have also tried a triangular mask that covers my whole nose, but it is very uncomfortable and also kind of noisy. While my wife wants me to use the mask for safety reasons, the noise is killing her, she can't sleep through the night now. What is the quietest mask that people have found to use? Preferably one with something to fix the mouth opening problem (like a chin strap, maybe?)

A chin strap is a separate thing than the mask itself, and it sounds like that is what you need. I use the PapCap chin strap--you'll find a lot of people on this forum prefer it. Another option is to consider a full face mask where it covers your mouth too.

Try the RespCare Hybrid Universal full-face mask: comfort of pillows and the security of not losing therapy air, no covering the nose or touching the forehead. Comes with 3 sizes of oral cushions and 3 sizes of pillows that can be adjusted to 2 heights. Lot of options that help make it fit most faces comfortably. Lot of us here wear it.

Our host sells it https://www.cpap.com/productpage/RespCa ... -Mask.html

What Muse said.

As long as you keep the vented air from hitting the hose, the pillow or the bed clothes (and that is something you have to make sure of with any mask). If make sure the hose comes from the direction of your chin, its a silent mask.

I use it with a hose hanger, leading the hose towards my chin in a J shape.