My girls, squeak, chirp, scream, huff through their cheeks and brux. Not necessarily in that order. They have lots of ways of communicating. Different squeaks mean different things. Each rat has a different voice. I can tell who it is even in the dark just by their voice.
Ben, especially is very communicative. Not only does he talk to me, when he walks up to me while in his out time, he puts his nose on my lips. It is his version of the way I kiss him. He pats my face with his warm little hands and never uses his claws unless his is concerned that he might fall.
Rats actually project feelings and ideas to me. If yours don't "talk" to you, you are not listening hard enough. It takes a quiet mind to listen to what they have to say.
Tell us why your rats are squeaking. What are the circumstances?