Articulation is one of the functions of Broca’s area of the brain, just forward of your left ear. Like an orchestra conductor, Broca’s area masterfully coordinates the diaphragm, larynx, lips, and tongue to create phonemes, the individual sounds within a language that are like the instruments in an orchestra.
Just as the strings make a different kind of music than do the brasses, and the brasses make a different kind music than do the drums, so also do the vowels in a language make a different music than do the fricatives, (those sounds that hiss or hush or buzz – like f,v, s, z, sh, th… Don’t just say these in your mind as you read that list. Go back and make the sounds they represent. Out loud, okay?)
The fricatives make different music than do the stops, (like p,b,t,d,k, and g.)
The stops make a different music than do the labials, etc.
Now here’s where it gets tricky. Some experts claim there are only 40 phonemes in the English language, while others claim there are as many as 48. It all comes down to whether or not the “th” in “with” is the same phoneme as the “th” in “the.” Stuff like that. “With” has an unvoiced “th” while the “th” in “the” is voiced.
Like Wizzo said in the memo, phonemes are a known and studied science.