Confusion around Hiatus Allotones in refgram/phonology/ #37
Description
The following phrases of the reference grammar— in the #allotones_sandhi section— have generated some confusion in the Discord channel #school and may be worth clarifying.
The rising-falling tone :d4: can optionally be pronounced as a falling-rising tone, or really any contour which contains a hiatus. Because of this, the :d4: tone is also known as the hiatus tone, after its defining characteristic.
When this allotone is used on a raku containing multiple vowels, the hiatus is inserted between the first and second vowel, and no additional hiatus needs to be inserted, because the first vowel already carries a stressed downward tone contour.
This seems to suggest that for any allotone of d4 realized on a word of which the first raku has two-or-more vowels, the hiatus should be inserted between those vowels, but that for the rising-falling allotone specifically, the hiatus should be inserted elsewhere.
Looking at the section on self-segregation in the Morphology chapter, we haven't been able to figure out why this should be the case; it seems like a stressed upward tone contour should behave the same as a stressed downward contour in this respect. If such a unique mapping of the rising-falling allotone is intended and/or necessary, a further explanation of what motivates that would be much appreciated in the text. If not, the section should probably be corrected.