I would recommend at least a 12x12x18high. They need to climb to be happy.
They have different calls. Some are loud croaks. Those crack me up! They go back and forth across the room like they are competing to see who is loudest. Then there are a series of song like croaks together. They make different noises when breeding also. Its a deeper flowing series of click-like croaks. My males, when being territorial of their females, croak loudly with a slightly quieter series of croaks flowing together after, while shaking their plant leaves. It's pretty neat to watch and listen to them. I'd love to speak to someone who actually studies their behaviors with the different croaks for true meaning.