Using Havana-born singer Aymée Nuviola (also known as La Sonera del Mundo) as an example, we might analyze her oral posture as the following:
LIPS: slightly pinned at the corners, but the lips move quite freely from lip corner retraction to lip corner protrusion
JAW: the jaw is slightly open and relaxed
TONGUE: the tongue is very active, often advanced, and cups deeply for sounds such as the Spanish /a/
VELUM (soft palate): The soft palate is slightly lowered, creating a channel for some nasal resonance in this accent
Oral Posture Quick Tip: The Thinking Sound
A clue to a speaker's oral posture can be their thinking or hesitation sounds, something every speaker has.
Thinking Sound #1 [ e̘ ]
Find the thinking sound by releasing the jaw open, and allow the tongue to advance far forward, and arch the front body of the tongue high at the front of the vocal tract. The tip of the tongue should be resting behind the bottom teeth.
Thinking Sound #2 [ aːm ]
Another possibility for this oral posture's thinking sound is one that utilizes the Spanish vowel /a/. Find this thinking sound by releasing the jaw open, and imagine that you are balancing a marble in the front/middle of your tongue, which creates a cupping action as you target this sound.
Slight lip rounding/relaxed cheeks
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 tongue often retracts or braces into the molars, which lends itself to the strong r-coloring of this dialect.
JAW: the jaw is fairly raised (closed)
Miami Thinking Sound [ ɑm ]
The target for the Miami thinking sound is a very open, unrounded back vowel. Think about cupping the back body of the tongue.