The form of intonation has now been described in some detail, and we will move on to look more closely at its functions. Perhaps the best way to start is to ask ourselves what would be lost if we were to speak without intonation: you should try to imagine speech in which every syllable was said on the same level pitch, with no pauses and no changes in speed or loudness. This is the sort of speech that would be produced by a "mechanical speech" device that made sentences by putting together recordings of isolated words. To put it in the broadest possible terms, we can see that intonation makes it easier for a listener to understand what a speaker is trying to convey. The ways in which intonation does this are very complex, and many suggestions have been made for ways of isolating different functions. Among the most often proposed are the following:

i) Intonation enables us to express emotions and attitudes as we speak, and this adds a special kind of "meaning" to spoken language. This is often called the attitudinal function of intonation.

ii) Intonation helps to produce the effect of prominence on syllables that need to be perceived as stressed, and in particular the placing of tonic stress on a particular syllable marks out the word to which it belongs as the most important in the tone-unit. In this case, intonation works to focus attention on a particular lexical item or syllable. This has been called the accentual function of intonation.

iii) The listener is better able to recognize the grammar and syntactic structure of what is being said by using the information contained in the intonation; for example, such things as the placement of boundaries between phrases, clauses or sentences, the difference between questions and statements, and the use of grammatical subordination may be indicated. This has been called the grammatical function of intonation.

iv) Looking at the act of speaking in a broader way, we can see that intonation can signal to the listener what is to be taken as "new" information and what is already "given", can suggest when the speaker is indicating some sort of contrast or link with material in another tone-unit and, in conversation, can convey to the listener what kind of response is expected. Such functions are examples of intonation's discourse function.

The attitudinal function has been given so much importance in past work on intonation that it will be discussed separately, although it should eventually become clear that it overlaps considerably with the discourse function. In the case of the other three functions, it will be argued that it is difficult to see how they could be treated as separate; for example, the placement of tonic stress is closely linked to the presentation of "new" information, while the question/statement distinction and the indication of contrast seem to be equally important in grammar and discourse. What seems to be common to accentual, grammatical and discourse functions is the indication, by means of intonation, of the relationship between some linguistic element and the context in which it occurs. The fact that they overlap with each other to a large degree is not so important if one does not insist on defining watertight boundaries between them.