One of the fundamentals of singing is to understand the real purpose of what is commonly called the mouth.
The mouth would be the area where we chew up our food! It involves the jaw, tongue, teeth, and lips. This mouth is different than the one where the vowels are shaped, the oro-pharynx area.
If the registration is correct for the given pitch and the vowel is properly shaped in relation to that pitch and “located” in the oro-pharynx, then the mouth where we chew food is free. Free to do what?
Well, it is free to properly add any finishing touches to certain vowels (does this less and less as one moves higher in pitch). It is also free to articulate with well-formed consonants which is the main purpose of our mouth in singing.
Say that the pitch and vowelled tone is set up nicely. The articulatory process would be found in the “chew food” mouth. The next steps concern the consonant, light and crisp, being mentally conceived. The consonant is then physically felt to be above the vowel which rests on the pitch step. The consonant is touching, not digging into, but touching the stream of vowelled tone and reflecting off.
Articulation of consonants is thus good to go, for the “chew food” mouth is now doing the vocal job it was meant to do!