Intonation units are an important component of American English pronunciation and speech. An intonation unit is a segment of speech. It can be as small as a single word, or as long as a sentence. Two sentences with identical grammatical structure may be comprised of differing numbers of intonation units when spoken, based on the intent or emotional state of the speaker. It's important to learn to distinguish these units because they give subtle meanings and help organize a conversation.

There is no single determiner as to where intonation units begin and end or how many a single sentence contains, but there are clues. Generally, intonation units:

• begin with faster speech, and end with slower speech
• include a single pitch word
• end with a pitch boundary

Intonation units and emotion

Individual speakers alter the number of intonation units they use. Some of this is based on individual patterns and habits, but speakers also alter intonation units based on emotion. A faster speaker will generally use fewer intonation units and may be seen as being more urgent, frantic, excited, and anxious. A slower speaker may have more intonation units and may be perceived as being more emphatic, determined, and insistent. Of course, these are the extremes, and most people normally speak somewhere in the middle range.

Elements of intonation units

Sentences can often be broken up into multiple intonation units. Each intonation unit usually has a single pitch word and ends in a pitch boundary. Each pitch word conveys information to the listener, and each pitch boundary helps organize how speakers take turns speaking.

The following examples show that similar sentences can have a different number of intonation units. The end of each intonation unit is marked with a hash ( / ) and the pitch words are bolded.

Notice that the speaker with fewer intonation units spoke faster, with fewer pauses, and with fewer changes in pitch during the statement.

The sentence with more intonation units sounds more emphatic and deliberate about what is being said. More intonation units can cause the entire conversation to occur more slowly. Speakers tend to match each other's English rhythm, so if one speaker has a more emphatic rhythm, it is likely that other speakers will mirror it.