When your cat meows but nothing comes out?
Some people think it is a yawn. Yawn's are obviously different than a meow as the mouth opens much further. I have a cat who I'll notice while looking at her... she opens her mouth as she would when meowing, but there is no sound what-so-ever. Sometimes she'll squeak, and the odd time she does meow quietly. Humans have various voices - One person is quiet, another is raspy... Cat's "voices' range too. However, if you are concerned... take your cat in for a vet visit. Most likely, it is nothing to worry about. You just have a quiet kitty :)