Sounds Your Joey Makes
Sugar gliders have very unique vocalizations and may startle you and your friends until you get used to them. Keep in mind that all sugar gliders have unique personalities, so you may or may not hear all of these sounds regularly.
Glider Love: Cricky & Pika
The most common sound you will hear is called crabbing; it sounds a lot like an electric pencil sharpener and can be quite loud. If your joey is crabbing, then it is probably feeling scared or startled; try to give it a little more space and approach it more slowly. Often, if it is really scared, it will also raise up onto its hind legs and hold its hands out as if to say "Stop!" At this point, it's a good idea to try a different approach, or you may get nipped. Try to pick up your joey from behind and gently scoop it up onto your hand and it won't be quite as scared. If you have more than one glider, you will hear crabbing much more often, as they like to "tell each other off" quite frequently: don't worry, this is perfectly normal, and they are not going to harm each other.
Your joey will also make a loud barking sound, like a small dog, in the middle of the night. Sometimes this is just to let you know that it wants attention or that it wants something to eat. Quite often, though, it is just happy and letting you know it! Mine usually bark at about 4 o'clock every morning. For this reason, I do not recommend putting your joey's cage in your bedroom!
Pierre peeks out of his pouch
Sugar gliders also make a type of hissing sound when they are first waking up. It sounds like a cross between a cat's hiss and a sneeze. This is their way of saying, "Hello, I'm up now!" One of my male gliders likes to hiss quite often just to let us know that he is awake. Some gliders also make this sound occassionally when they urinate. (If your glider ever hisses frequently while urinating, then it may have a Urinary Tract Infection and should be seen by a vet immediately for diagnosis.)
You may also hear a small chirping and/or clicking noise combined with a softer hiss. This sound can be heard most often when they are cuddling up to go to sleep. I personally love this sound the most, since it means that my glider feels secure enough with me to cuddle up to me. It reminds me of a cat's purring because it indicates contentment.