PRE-LAPS & CHYRONS
STARTING THE SCENE BEFORE THE SCENE
As you can see, Dara's line is actually said in Alfonso's room, but for effect, we hear it before we cut to the room. It's a sound transition from one scene to the next and it's perfectly "legal" in a spec script.
The second method is exactly the same, except you replace the V.O. with the term PRE-LAP.
If the sound is not dialogue, you can use the PRE-LAP as follows:
PRE-LAP - A dog BARKS followed by a SCREAM and a CRASH.
INT. ALFONSO'S KITCHEN - DAY
Alfonso lies on his back -- a St. Bernard licking his face. Grocery bags are scattered across the floor.
FOR CHYRON OUT LOUD
CHYRON: "Did I just say that?"
You could also format it as you would a text message, if you prefer.
The term also refers to the text-based graphics that appear at the bottom of your TV during a news broadcast.