Is it true that dramatic irony allows the audience to know more than the characters who speak?
Dramatic irony means that the audience knows what is going on, but the characters do not.
Dramatic irony can be either funny or tragic. Basically, it means that in a prior scene, or from another character, the audience or reader learned a crucial piece of information that the other characters do not know.
A good example of this is Shakespeare's Macbeth. Macbeth tells the audience in an aside that he wants to be king, and is in fact burning with the desire. He writes a letter to his wife Lady Macbeth, who comments that her husband is ambitious, though she worries that he is not ambitious enough. It is clear that she too wants to kill the king. Macbeth and Lady Macbeth discuss killing the king.
Then the king, Duncan, arrives, but he gives a little speech about how great Macbeth’s castle is and how happy he is to be there.
This is an example of dramatic irony, because Duncan has no idea that this castle is not as pleasant as he thinks it is, since his hosts want to kill him! The audience knows, however. Lady Macbeth and Macbeth are plotting Duncan’s murder, just as he talks about how hospitable their house is.
Dramatic irony is very useful in increasing the suspense of a play or story. It can be used in books as well as plays and movies. Any time the audience or reader learns information that is kept from some of the characters, that adds to the investment the audience or reader has in the story. It makes the story more interesting as the audience or reader wonders how the secret, privileged information will pan out. It’s like being in on the joke!