Your cat has a voice. You can most likely distinguish the vocalizing of one cat in your household from the others—maybe even from some of the neighborhood cats who speak to you from outside.
Granted, most cats are fairly quiet. They only spea when they have someone in particular on their mind like eating—“Right Meow!” Olivia isn’t very vocal, but she uses what voice she has—a high pitched mew—almost every day to entice me to get up out of my office chair and play with her.
You may have also heard your cats chirp, squeal in delight (as Olivia does when she leaps up against the walls—I still don’t know what that’s all about). Cats purr, of course, make a little clicking sound when watching a bird out through a window, and they can cry out in pain, although they’re usually quiet when they’re hurting. I imagine that’s an inbred reaction to protect themselves from predators when they are vulnerable. Step on a cat’s tail, though, and you’ll hear that squeal.
Sure, you’re familiar with the sounds your cat makes, but did you know they are capable of making 11 different sounds. Neither did I. (Another source says they make up to 20 different sounds.) Here’s a link that explains some of them. It’s rather interesting.