Intonation is very important in communication as it gives information beyond just the basic meaning of the words. It can express the speaker's attitude or feeling about something, as well as giving grammatical information (such as distinguishing between a statement and a question).
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intonation is important in spoken English because it conveys meaning in many ways. Changing the pitch in your voice – making it higher or lower - allows you to show surprise “Oh, really!” or boredom “Oh, really.