What are some important literary devices in Act 2 Scene 2 of Macbeth?

Some important literary devices at work in Act 2 Scene 2
of Macbeth are as
follows:

Symbolism:  Near the
beginning of the scene, Lady Macbeth claims that she heard an owl shrieking, and she
calls it the "fatal bellman."  The owl is a symbol for the death of
Duncan. 

Allusion:   Later in
the scene, Macbeth refers to "great Neptune's ocean" which is a reference to the Roman
god of the sea.

Metaphor:   
Lady Macbeth is disappointed in her husband's cowardice and says, "I shame to wear a
heart so white."  The color white is a metaphor for fear and
innocence.

Extended metaphor: 
Macbeth talks of "murdering sleep" throughout the scene.  He uses sleep
as a metaphor for peace, meaning that since he has committed such an evil crime, he will
no longer have peace of mind.

Irony: 
Later the audience learns that the knocking on the door is from Lenox and
Macduff who are arriving at Inverness.  However, Macbeth is in a state of frenzy and
believes that someone has heard him commit the murder--the audience, however, is fully
aware that no one else knows of Macbeth's crime.