Vocal communication involves caterwauls for mating, chattering upon spotting prey, hissing to ward off an intruder, or shrieking when hurt or terrified. Meowing is not part of this language. Meow-ese, it would seem, is a language developed exclusively for humans.
How fascinating! The article goes on to discuss research into this inter-species communication, and how cat owners are better at understanding the emotion being conveyed by a particular caterwaul.
Very interesting, even if completely obvious when you think about it.
petcentric: Your Bi-Lingual Kitty