In the previous scene, which occurs during and immediately following Macbeth's murder of Duncan,Lady Macbeth is frightened by the same owl—"the obscure bird" that "Clamor'd the livelong night. (2.3.60-61)—that Lennox mentions later to Macbeth.

LADY MACBETH. ...Hark! Peace!
It was the owl that shriek'd, the fatal bellman,
Which gives the stern'st good-night. (2.2.3-5)

When Macbeth comes back to Lady Macbeth from Duncan's rooms after the murder, he asks Lady Macbeth if she heard anything in the night. She responds that she heard nothing more than the usual night sounds, although she interprets the sounds as bad omens.

MACBETH. ...Didst thou not hear a noise?

LADY MACBETH. I heard the owl scream and the crickets cry. (2.2.18-19)

Macbeth himself, intent solely on the murder of Duncan, heard nothing other than the voices of Duncan's guards crying out in their sleep and praying, and voices in the distance, crying out that "Macbeth doth Murder sleep."

MACBETH. There's one [of Duncan's guards] did laugh in's sleep, and one cried, “Murder!”
That they did wake each other: I stood and heard them:
But they did say their prayers and address'd them
Again to sleep... (2.2.30-34)

MACBETH. Me thought I heard a voice cry “Sleep no more!
Macbeth doth Murder sleep”—...

Still it cried, “Sleep no more!” to all the house;
“Glamis hath murdered sleep, and therefore Cawdor
Shall sleep no more. Macbeth shall sleep no more.” (2.2. 45-46, 53-55)

Otherwise, Macbeth and Lady Macbeth are so focused on Duncan's murder that they're seemingly oblivious to anything that occurs outside their castle. Their solitude is preserved until the outside world comes to them when Macduff starts knocking at the castle gate.

In act 2, scene 4, Shakespeare emphasizes the portentous events that occurred during the night by having Ross and an Old Man discuss strange and troubling events that they, too, experienced.

ROSS. ...Thou seest the heavens, as troubled with man's act,
Threaten his bloody stage. By the clock ’tis day,
And yet dark night strangles the travelling lamp.
Is't night's predominance, or the day's shame,
That darkness does the face of earth entomb,
When living light should kiss it?

OLD MAN. ’Tis unnatural,
Even like the deed that's done. On Tuesday last
A falcon towering in her pride of place
Was by a mousing owl hawk'd at and kill'd. (2.4.6-15)

Ross brings the outside events even closer to the events that occurred inside Macbeth's castle by relating an incident involving Duncan's horses.

ROSS. And Duncan's horses—a thing most strange and
certain—
Beauteous and swift, the minions of their race,
Turn'd wild in nature, broke their stalls, flung out,
Contending ’gainst obedience, as they would make
War with mankind.

OLD MAN. ’Tis said they eat each other.

ROSS. They did so, to the amazement of mine eyes
That look'd upon't. (2.4.16-24)

It's hard to believe that Duncan's horses actually ate each other, but Lennox reported a violent storm which very likely frightened the horses to such an extent that they broke out of their stalls. Ross might have been simply exaggerating the horses's activities fighting and biting each other.

Nevertheless, the events reported by Lennox, Ross, and the Old Man show that the world outside the castle walls was undergoing a disastrous upheaval, which Macbeth and Lady Macbeth were wholly unaware had been caused by their murder of Duncan.

In Shakespeare's Macbeth, comparing Act Two, scene two and theMacbeths' experiences, and Act Two, scene three and Lennox'sobservations, it is safe to say that both evenings seem to be controlled by chaos and death.

It is, of course, in Act Two, scene two, that Mabeth and his wife carry out the murder of King Duncan. Macbeth is greatly disturbed by what he has done: sounds nearby distress him enormously. He returns from the scene of Duncan's death, and his warrior's courage has deserted him—perhaps because he has not acted honorably and bravely for his King, but is a dishonorable, frightened murderer of his King.

As soon as the King has been killed, nature reflects an imbalance within the world: Elizabethans believed that once Duncan was killed, the world was out of sorts. They felt that God ordained who came to the throne, not men. In this case, however, Macbeth has taken the God-chosen King from the throne, disrupting the Great Chain of Being. (Until the throne is once again in the hands of the rightful heir to the throne, this imbalance will not end.)

It is important to note that in line fifteen of this scene, as Macbeth returns and wonders fearfully what sound he has heard, Lady Macbeth responds that she heard an owl's scream (a harbinger of death) as well as the sound of crickets "crying." Macbeth then recounts what happened as he carried out the deed: while the guards spoke in their sleep, calling out, "Amen," Macbeth was unable to do so. He seems unaware that murdering his King mightseparate him from the will of God, and that his creator might be far-distanced from the man who has killed His chosen ruler of Scotland.

Macbeth has also, to his wife's horror, brought the murder weapons back with him. He refuses to put them back:

I'll go no more:
I am afraid to think what I have done;
Look on't again I dare not. (50-52)

In the following scene (three), Lennox comments on the behavior of nature and its creatures the night before, saying that the night was "unruly." Lennox describes a terrible wind that knocked down a chimney. Others reported that they heard "wailing" (lamenting) and "strange screams of death," and even an earthquake. The term "confused events" translates to "disorder," which reflects thedisruption of order that Macbeth's actions have caused. And again, the screams of the owl are heard.

While this might foreshadow the discovery of Duncan's murder, it also parallels what was occurring immediately after Macbeth killed the King.

Interestingly, Macbeth in scene two is in much the same condition as the guards when they are "discovered." When Macbeth returns to his chambers, he is covered with Duncan's blood—looking fearful. His wife tells him: "Go get some water, / And wash this filthy witness from your hand." We can imagine that he is distracted as well: he is hearing noises and rambles on about prayers he can't say and voices he hears (in his head?) that whisper "Macbeth does murder sleep..." He is frantic, and even refuses to return the murder weapons to Duncan's room.

When the guards wake in the morning to the ravings and clamoringaround them, they are much the way Macbeth was the previous night: they are confused, covered in blood, and giving the appearance of being dangerous...

They stared and were distracted, no man's life
Was to be trusted with them. (114)

Ironically, these descriptions of Macbeth the night before and the guards the next day are very similar, as are the sounds heard during the night.