intonation has been Discourse Intonation, an offshoot of Discourse Analysis first put forward by David Brazil. This approach lays great emphasis on the communicative and informational use of intonation, pointing out its use for distinguishing between presenting new information and referring to old, shared information, as well as signalling the relative status of participants in a conversation (e.g. teacher-pupil, or doctor-patient) and helping to regulate conversational turn-taking. The description of intonation in this approach owes much to Halliday. Intonation is analysed purely in terms of pitch movements and "key" and makes little reference to the other prosodic features usually thought to play a part in conversational interaction. American approaches The dominant framework used for American English from the 1940s to the 1990s was based on the idea of pitch phonemes, or tonemes. In the work of Trager and Smith there are four contrastive levels of pitch: low (1), middle (2), high (3), and very high (4). (Unfortunately, the important work of Kenneth Pike on the same subject had the four pitch levels labelled in the opposite way, with (1) being high and (4) being low). In its final form, the Trager and Smith system was highly complex, each pitch phoneme having four pitch allophones (or allotones); there was also a Terminal Contour to end an intonation clause, as well as four stress phonemes. Some generalizations using this formalism are given below. The American linguist Dwight Bolinger carried on a long campaign to argue that pitch contours were more important in the study of intonation than individual pitch levels. Normal conversation is usually at middle or high pitch; low pitch occurs at the end of utterances other than yes–no questions, while high pitch occurs at the end of yes–no questions. Very high pitch is for strong emotion or emphasis. Pitch can indicate attitude: for example, Great uttered in isolation can indicate weak emotion (with pitch starting medium and dropping to low), enthusiasm (with pitch starting very high and ending low), or sarcasm (with pitch starting and remaining low). Declarative sentences show a 2–3–1 pitch pattern. If the last syllable is prominent the final decline in pitch is a glide. For example, in This is fun, this is is at pitch 2, and fun starts at level 3 and glides down to level 1. But if the last prominent syllable is not the last syllable of the utterance, the pitch fall-off is