In general rats are very quiet animals, it's extremely uncommon that they're going to make noise. There are no typical vocalizations that you should expect on a regular basis from your rat. What you should expect is vocalizations that tend to be related to concerns such as, crying out in pain, if for example they were to get a toe caught in the cage or break a toe nail, or injure themselves. They do sometimes vocalize or squeak and make sort of a high pitch squeaking type of sound. If they become very scared, if they become nervous, when they're sometimes first handled, or somebody takes a rat out of the home the rat becomes nervous. And for example they go to the veterinarian and when their first picked up, they may vocalize, squeak a little bit, and make a few sounds, but basically that's about the most sound that they are going to make.
Sort of a short squeak of vocalization. A little bit of a warning type of sound that either indicates that something scared them, something has hurt them, or they've injured themselves and their alerting you to that. Most of the time a lot of the cues that rats have for each other relate to body language, and recognition of certain movements, and certain gestures. They don't tend to have a vocal or spoken language. Most of the time vocalizations that are short squeaks relate to an out cry, a warning, or fear type vocalization.