This is common and the larger the snake, the louder the sound will be. They breath air like we do and when they are climbing, griping and doing their thing you will hear that exhale sound.
There is a video on You Tube of a huge retic crawling around, and it sounds like an air conditioner!
No worries unless it is wheezing or popping. Regular air exchange is not a concern.
Boas are also pretty good about letting you know when they are not happy.
Reply With Quote