It has been previously proposed that syllable and word boundaries in Gregorian chant texts can be used to segment chant melodies in a more meaningful way than segmentation methods that do not take textual information into account, based on how accurately the mode of a melody can be determined from the presence of such melodic segments. This was evidenced by empirical measurements on antiphons and responsories with fully transcribed melodies available from the Cantus database.
We show that for antiphons, however, this result does not hold, as in these experiments, differentiae were not removed from the transcribed melodies. With appropriate data cleaning, the modality of a melody can be determined from segments that ignore textual boundaries just as accurately, and the resulting classification scores are not significantly better than those obtained from pitch profiles.
Thus, while the idea is clearly attractive, there is currently no reason to suspect that textual boundaries lead to a more meaningful segmentation of chant melodies.