In my previous post on intonation, I talked about the phonological paragraph and how intonation can be used to segment these in a presentation. This is an important device that an expert presenter will use to give their talk structure and coherence
In this post, I’d like to discuss in more detail about how intonation develops over a group of words, usually termed the tone unit. A tone unit is the minimal unit which can carry intonation. It can be one syllable long, but usually extends over a few syllables. (A tone unit can also be called an ‘intonation unit’ or ‘foot group’.)
A tone unit can be defined as follows:
[A tone unit] is a stretch of speech uttered under a single coherent intonation contour. It tends to be marked by cues such as a pause and a shift upward in overall pitch level at its beginning, and a lengthening of its final syllable.
DuBois et al (1992:17)
Structure of the Tone Unit
The structure of the tone unit is as follows. The tonic syllable is obligatory but all other parts are optional.
(PH) (H) TS (T) (pre-head) (head) tonic syllable (tail)
- tonic syllable: ‘carries’ the tone. Is obligatory
- head: all stressed syllable up to (but not including) tonic syllable
- pre-head: any unstressed syllables before the head
- tail: any unstressed syllables that follow the tonic
Examples of Tone Units
Some examples of tone units are given below. In the first example, the tone unit is a single syllable ‘those’. This is the tonic syllable and in this cases has been given a falling intonation denoted by \
1.| \those | 2.| 'give me \those | 3.| in a 'little 'less than an \hour | 4.| and then 'I said my \father was here |
In the second example, the tonic syllable is preceeded by a head ‘give me’. ‘Give’ is stressed so is the start of the head. In the third example, the tonic is ‘hour’, the head is ‘little less than an’ and the pre-head is ‘in a’. Note the pre-head does not contain any stressed syllables. In example 4, the tonic ‘father’ is followed by a tail ‘was here’.
Every tone unit has a single intonational contour. In other words, the listener will perceive a major change in tone (pitch of voice) somewhere within the tone unit. This change of tone occurs on the tonic syllable and thus we say that the ‘tonic carries the tone’. However, if there is a tail, then the change in the tone may continue over the tail.
A speaker can change the tonic syllable to emphasise different words in the unit. In the following examples the change in tone occurs on different syllables within the tone unit and thus the listener perceives a different emphasis on each one.
| and then I \said my father was here | | and then I said my \father was here | | and then I said my father was \here |
A further notion is the idea of key. Key is a feature of the the head of the tone unit. The key can be high, medium or low. A high key tone unit means that the head starts at a high pitch before changing on the tonic. High pitch is relative here and depends on the speaker’s voice and also the surrouding context.
For a post on identifying tone unit borderline cases, see here.
Du Bois, J. W., Cumming, S., Schuetze-Coburn, S. & Paolino, D. (1992), Discourse Transcription, Santa Barbara Papers in Linguistics, 4, Department of Linguistics, University of California, Santa Barbara, CA.
Roach, P. (2001) English phonetics and phonology: A practical course. Cambridge University Press