My cat does the silent meow thing. I think the Big Mew did a deal with him, my kitty, before we brought him home.
Miss Molly does a silent meow thing too. Most of the time no sound comes out at all. And then, every once in a while, as I’m reading or watching tv in the living room, the house shakes with this thunderous piteously long wooooing sound! LOL Molly for heaven’s sake. She tucks herself in the bathroom down the hallway, pokes her head out like a gopher in a hole and lets loose. It sounds like a fog horn from the grave! LOL LOL Oh, kitty cats. Full of surprises.