I have heard a variety of sounds
and note what is going on when they make them and came to a few conclusions myself with Arwen, keeping in mind that not every glider is the same and may make different sounds
for different reasons than other gliders.
we all know the bark and crab so will skip that.
clicking. click two of your fingernails together quite fast and that is a close copy of the clicking sound. generally menas "hi happy to see you" or in the case of ONE of mine "I like the way that smells"
popping. a very slow soft type of click that sounds
like a piece of popcorn popping under a blanket. or soft bubbles. Always made when sleeping in the pouch and I stick my hand in and massage them. have heard the popping change to clicks quite quickly if they wake up so assume the popping is a "sleepy" form of click.
chittering. made when eating something really yummy. figure it means "yummy" or "mine dont take this and give me another". sounds
like a series of differently pitched chirps.
whispers. only my Arwen out of my gliders does this. it is sort of a soft, very soft, sort of chittering. done very "airy" like a soft whisper. only time she does it is to me. so I feel its something special for me alone and she is trying to tell me something because she will get right up to my face and look at me very intently and whisper away. I will whisper back to her and she seems happy and then goes about her business. does it mostly when she sees me after not being together a long time (like half a day LOL)
the buzz. this is hysterical! only two who do it is Arwen and her dad. when they are chasing something (hand, feather, whatever) and get going VERY fast and are getting very intent on the catch. maybe even mad as we are not letting them catch it, they make a loud buzz. we almost freaked the first time as it is very odd. like a crab sound speeded up very fast to all run together to make a buzz almost like a wasp does when flying. very funny indeed!
in addition they do make a variety of other sounds
and combinations I just cant explain here.