We have seen that the 2-and 3-place components […] and the fixed-sequence components […] differ in effect, in that the former describe limitations of distribution and the latter describe contours. It is of interest to notice wherein these two types of long components differ structurally and wherein they are similar. They are similar in that they are all expressions for limitations of distribution of different segments. In the case of the pitch contours, we begin with allohponic segments that contain pitch and stress features in them. We notice that there are limitations upon the distribution of these segments. For instance, after a sequence of segments in which each loud-stressed segment is higher-pitched than the preceding, we never get a low-pitched segment: after 'Is your brother?' We never get a low 'going' which is pitched even higher than 'brother'. And in 'Is your brother going?' We do not get a low pitched 'ing'. We express this limitation of distribution by saying that all the segments of the utterance contain a particular component in common, and that this component has various phonetic values at various parts of its stretch: low pitch on the first low-stressed vowel, higher pitch on the next, etc. Exactly this is what we do with the 2-and 3-place components: We notice that after /s/ we never have /b/, but only /p/. We express this by saying that both successive segments have a particular component in common, and that this component has fortis value throughout its stretch. The differences between the two types of long components are four.
- Harris (1944), Pag. 202, n.22