Oral posture refers to a dialect or accent's "home base" in terms of articulatory settings - specifically the jaw, the lips, the tongue, the cheeks, and the velum (soft palate).
Some features of the oral posture for a Miami dialect, using as examples Gloria Estefan and Jenny Lorenzo, a Cuban-American comedienne from Miami.
LIPS: slight lip corner protrusion, but the body of the lips remains pretty relaxed
VELUM (soft palate): lowered, which creates a channel for nasal resonance
CHEEKS: very relaxed
TONGUE: The tip of the tongue is active, which lends itself to the use of the Spanish L in many words.
JAW: the jaw is fairly raised (closed)
For each sound, I’ve included audio examples and practice phrases. Unless otherwise indicated, practice phrases are excerpted from Lexical Sets for Actors by Eric Armstrong under a creative commons license.
Words like BATH/TRAP/TRAM --> [ ä ]
This is an open vowel that tends to be more centralized - think about targeting a Spanish A in the center of the vocal tract with a cupped tongue.
Words like GOOSE --> [ u̘ ]
This vowel will become fronted in the Miami dialect, meaning the vowel is pronounced high and forward in the vocal tract.
Words like GOAT --> [ o̝ ]
The target for this sound is a rounded vowel, the back body of the tongue is high and arched in the back.
Words with L
When L is the first letter in a word, or occurs in the middle of a word, the pronunciation of this consonant is similar to the L in Spanish.
The prosody, or musicality, of the Miami dialect is heavily influenced by close contact with Spanish, which results in syllable-timing.