The aim of this paper is to explore the possibility of using rhythm metrics on the traditional units of speech rhythm (the syllable and the foot), instead of applying them to consonantal and vocalic intervals. Despite  had already proven that the standard deviation of syllables and feet did not provide a satisfactory representation of the traditional rhythm classes, some recent studies obtained encouraging results. In particular,  applied the PVI to English and Estonian syllables and feet, and a similar approach is intrinsic in the YARD index (cf. ) though only at syllable level. We computed the deltas and the PVIs on syllables (measured as the distance between two successive vocalic onsets) and feet (measured as the distance between the onsets of two stressed vowels) for 30 samples of 14 languages.
The results do not confirm expectations and do not seem to support the use of these units for the study of speech rhythm in these terms.
Bibliographic reference. Mairano, Paolo / Romano, Antonio (2011): "Rhythm metrics on syllables and feet do not work as expected", In INTERSPEECH-2011, 1857-1860.