Linguistics; ET languages, continued...

In a recent post, I said:
"Suppose you encounter a language that has three basic classes of meaningful sounds: vowels, consonants -- and something else. The question then is: What could that 'something else' be?" Now I'm not quite sure what to do with the blogmonster I managed to create with that question.

One possibility is to take up each of your comments, one at a time, and respond in detail. That means finding a way to explain a great deal of basic information about phonetics and phonology...