The rhythm of Much Ado about Nothing, which is continued in Act IV, scene i, is that of iambs. Iambs describe a rhythm that is duple, having two beats to each unit of rhythm. It is described as an unstressed beat followed by a stressed beat and is thought to be the rhythm closest to the spoken form of English. We'll use Hero's line in the middle of the scene to illustrate iambs. An unstressed beat is shown by this sign ^ and a stressed beat is shown by this ':
They^ know' that^ do' ac^ -cuse' me^; I' know^ none'
You can see that the duple rhythm of unstressed stressed repeats, in fact, it repeats five times yielding the poetic meter called pentameter--or five measures of repeated rhythm.
Shakespeare usually uses line-end punctuation, seldom utilizing enjambment. Enjambment is when the thought of one poetic line continues in the following line and thus has no line-end punctuation. This same speech of Hero's shows both enjambment and line-end punctuation. There are three enjambed lines. They are:
1) If I know more of any man alive
2) Prove you that any man with me conversed
3) At hours unmeet, or that I yesternight
Each of these has a thought that is carried on in the next line, for instance:
If I know more of any man alive
Than that which maiden modesty doth warrant,
Line-end punctuation ends the current thought and is such as you are familiar with from your prose reading. A couple of examples of line-end punctuations that end thoughts that do not carry on in the next line are:
1) They know that do accuse me; I know none:
2) Than that which maiden modesty doth warrant,
Shakespeare also uses punctuation in a medial (middle) position. This can either end a thought in mid-line or can designate parts of a thought, just as in prose. An example of the first is: "Let all my sins lack mercy! O my father, ...." Examples of the second are:
1) At hours unmeet, or that I yesternight
2) Refuse me, hate me, torture me to death!