I have a female cat named Kiki who can meow normally but also will "silent meow" every once and a while. She's been doing that for the last 15 years. I also have another female cat named Tootsie who can't meow normally at all. Whenever she tries, she sounds like she's gargling. When we asked our vet, he said cats have two vocal cords, one for purring and one for meowing. He said the one for meowing was probably damaged when she was a kitten by an infection (we found her when she was about a teenager). But she has the ability to purr.