I now turn to the cases where Petrocchi has a diaeresis in a final falling diphthong followed by a sinalefe, and where I believe, in line with the practice of Antonio Lanza's recent re-edition of the Comedy, (23) that it is better to assume synaeresis followed by dialefe.
If these thirty cases are left on one side, it can be seen that the greater number of exceptional sinalefi in this category of polysyllables comes after final accented single vowels rather than final accented falling diphthongs, of which there are only four instances with sinalefe above (3, 10, 14, and 22), if we exclude cases where the final vowel of the diphthong has been elided (2, 23, 25).
The important issue is that final accented falling diphthongs followed by an initial vowel regularly count as two syllables in the Divine Comedy, and it seems reasonable to conclude that they should all be treated in the same way, either as diaereses followed by sinalefe or as synaereses followed by dialefe; my own preference, which I have adopted throughout, is for the latter, as the simpler and more consensual solution.
Such handling of falling diphthongs is standard for all genres of florid singing, and will be recognized by anyone with even a basic exposure to such styles of Italian singing.
The principal reason for splitting falling diphthongs into two categories, as mentioned earlier, was to determine whether those ending in <a>, <e>, or <o> were treated differently than those ending in the "reducible" (i.e., "glide-able") vowels <i> and <u>.
Three other results were obtained from the study of this category of falling diphthongs.
The unstressed initial syllable arguably does not contain equally stressed vowels, and can be considered a reduced form of falling diphthong. In the speech of many Italians, the initial semiforte vowel will be as strong as the tonic syllable.
In such instances, the quarter note divides into two eighths, with stress assigned to the former vowel, in the manner of a falling diphthong.
Again, the verb e takes priority over the following [a], the two behaving as a falling diphthong. The [a] of fredda forms a rapid appoggiatura before the beat, or else disappears completely, like the apocopated [i] in her next utterance, Io non gliel' sento.
The reader may know intuitively through experience that some falling diphthongs have their coda semivowels regularly rhythmicized by composers and assigned a separate note, while others are rarely (if ever) treated in such manner.
Believing all vowel clusters to be iati unless containing an <i> or <u>, he doesn't discuss the possibility of <ea> and <eo> as falling diphthongs
, with the first vowel syllabic.