If we think of linguistic analysis as usually being linked to the sentence as the maximum unit of grammar, then the study of discourse attempts to look at the larger contexts in which sentences occur. For example, consider the four sentences in the following:

A: Have you got any free time this morning?

B: I might have later on if that meeting's off.

A: They were talking about putting it later.

B: You can't be sure.

Each sentence could be studied in isolation and be analyzed in terms of grammatical construction, lexical content, and so on. But it is clear that the sentences form part of some larger act of conversational interaction between two speakers; the sentences contain several references that presuppose shared knowledge (e.g. 'that meeting' implies that both speakers know which meeting is being spoken about), and in some cases the meaning of a sentence can only be correctly interpreted in the light of knowledge of what has preceded it in the conversation (e.g. 'You can't be sure').

If we consider how intonation may be studied in relation to discourse, we can identify two main areas: one of them is the use of intonation to focus the listener's attention on aspects of the message that are most important, and the other is concerned with the regulation of conversational behaviour. We will look at these in turn.

In the case of "attention focusing", the most obvious use has already been described: this is the placing of tonic stress on the appropriate syllable of one particular word in the tone-unit. In many cases it is easy to demonstrate that the tonic stress is placed on the word that is in some sense the "most important", as in:

She 'went to Scotland

Sometimes it seems more appropriate to describe tonic stress placement in terms of "information content": the more predictable a word's occurrence is in a given context, the lower is its information content. Tonic stress will tend to be placed on words with high information content, as suggested above when the term focus was introduced. This is the explanation that would be used in the case of the sentences:

i) Ive 'got to 'take the dog for a -walk

ii) Ive 'got to 'take the 'dog to the wet

The word 'vet' is less predictable (has a higher information content) than 'walk'. However, we still find many cases where it is difficult to explain tonic placement in terms of "importance" or "information". For example, in messages like:

Your coat's on fire                           The wing's breaking up

The radio's gone wrong                  Your uncle's died

probably the majority of English speakers would place the tonic stress on the subject noun, although it is difficult to see how this is more important than the last lexical word in each of the sentences. The placement of tonic stress is still to some extent an unsolved mystery; it is clear, however, that it is at least partly determined by the larger context (linguistic and non-linguistic) in which the tone-unit occurs.

We can see at least two other ways in which intonation can assist in focusing attention. The tone chosen can indicate whether the tone-unit in which it occurs is being used to present new information or to refer to information which is felt to be already possessed by speaker and hearer. For example, in the following sentence:

'Since the vlast time we .met | 'when we 'had that 'huge vdinner | Ive ,been on a diet

the first two tone-units present information which is relevant to what the speaker is saying, but which is not something new and unknown to the listener. The final tone-unit, however, does present new information. Writers on discourse intonation have proposed that the falling tone indicates new information while rising (including falling-rising) tones indicate "shared" or "given" information.

Another use of intonation connected with the focusing of attention is intonational subordination; we can signal that a particular tone-unit is of comparatively low importance and as a result give correspondingly greater importance to adjacent tone-units. For example:

i) As I ex.pect youve heard I theyre 'only ad'mitting emergency -cases

ii) The 'Japavnese I for ,some ,reason or /other I 'drive on the left I like us

In a typical conversational pronunciation of these sentences, the first tone-unit of (i) and the second and fourth tone-units of (ii) might be treated as intonationally subordinate; the prosodic characteristics marking this are usually:

i) a drop to a lower part of the pitch range ("low key");

ii) increased speed;

iii) narrower range of pitch; and

iv) reduced loudness, relative to the non-subordinate tone-unit(s).

The use of these components has the result that the subordinate tone-units are less easy to hear. Native speakers can usually still understand what is said, if necessary by guessing at inaudible or unrecognizable words on the basis of their knowledge of what the speaker is talking about. Foreign learners of English, on the other hand, having in general less "common ground" or shared knowledge with the speaker, often find that these subordinate tone-units - with their "throwaway", parenthetic style - cause serious difficulties in understanding.

We now turn to the second main area of intonational discourse function: the regulation of conversational behavior. We have already seen how the study of sequences of tone-units in the speech of one speaker can reveal information carried by intonation which would not have been recognized if intonation were analyzed only at the level of individual tone-units. Intonation is also important in the conversational interaction of two or more speakers. Most of the research on this has been on conversational interaction of a rather restricted kind - such as between doctor and patient, teacher and student, or between the various speakers in court cases. In such material it is comparatively easy to identify what each speaker is actually doing in speaking - for example, questioning, challenging, advising, encouraging, disapproving, etc. It is likely that other forms of conversation can be analyzed in the same way, although this is considerably more difficult. In a more general way, it can be seen that speakers use various prosodic components to indicate to others that they have finished speaking, that another person is expected to speak, that a particular type of response is required, and so on. A familiar example is that quoted above (p. 156), where the difference between falling and rising intonation on question-tags is supposed to indicate to the listener what sort of response is expected. It seems that key (the part of the pitch range used) is important in signalling information about conversational interaction. We can observe many examples in non-linguistic behavior of the use of signals to regulate turn-taking: in many sports, for example, it is necessary to do this - footballers can indicate that they are looking for someone to pass the ball to, or that they are ready to receive the ball, and doubles partners in tennis can indicate to each other who is to play a shot. Intonation, in conjunction with "body language" such as eye contact, facial expression, gestures and head turning, is used for similar purposes in speech, as well as for establishing or confirming the status of the participants in a conversation.