Often the omitted syllables are a vowel at the end of a word which is followed by a vowel at the beginning of the next one, it's a very simple elision that would happen in every day speech. For example: the phrase "Patri et Filio", in a doxology is sometimes seen. This would mean to make two syllables-"Patr' et", rather than the usual three.

I find that the italicized consonants are just as well omitted. I don't get too worried about this. When we speak English w' elid-and contract and omit things all ov'r the place, simply 'cause we know how th' language works - I'm sure tha' th' people-who daily spoke Latin and wrote these hymns understood how th' language work'd, and simply wrote how they spoke in ev'ryday life.

The most-used chant that I can think of in which this sort of elision happens all the time is the Veni Creator Spiritus.

The problem of singing these notes is that it can destroy the stophic nature of the Hymn. With Hymns the repeating melody is usually more important than the words.

'Tu-ae ad' would be sung as 'Tu- ad' (Not singing the extra note).

The words aren't just there to decorate the music. In the liturgy, the words are part of the rite itself. Omitting one or two syllables would be like the priest omitting a gesture or a word in his prayers. Especially in a Missa Cantata (or higher), or in EF vespers, the text simply must be complete.

May 14, 1915, Decree Dubium, no. 4329
The question was asked of the Congregation of Sacred Rites:
Whether the regulation given in the Vatican Antiphonary about hypermetric syllables which occur often in the singing of hymns—that is, these syllables are not to be elided but are to be distinctly pronounced and sung on their own notes—whether or not this regulation is to be interpreted strictly, or whether on the contrary it is permissible to slur over these syllables, especially if this practice is thought easier and more convenient?
The same Congregation ... issued the following Rescript on the question, which had been carefully considered:
To the first part, No; to the second part, Yes. 175
Papal Legislation on Sacred Music

In some languages, 'omitting' some syllables in some circumstances is simply how the language is spoken. It isn't an omission so much as a consequence of the fact that written language imperfectly mirrors spoken language.

(Maybe this is true of all languages -- I'm not a linguist.)

(Added as an edit) A few illustrative examples from Latin that are commonly found in ancient texts (both prose and poetry, but most often in poetry, which makes sense, of course, because it was intended to be read aloud and so would be written to more closely match what is (properly!) said):

animadverto for animum adverto
antea for ante ea
circitor for circum itor

and so on. There are tons of them.

My Liber has the question put to the S.R.C. as:

<<An regula descripta in Antiphonario Vaticano circa syllabas hypermetricas, quae frequenter occurrunt in cantu hymnorum, scilicet quod ipsae non elidantur, sed distinctae pronuncientur propriaque nota cantentur, stricte et rigorose interpretanda sit, vel e contra liceat etiam ipsas syllabas elidere, praesertim si in praxi id facilius et convenientius censeatur?>>

To which the answer is

<<Negative ad primam partem, affirmative ad secundam>>.

So the Latin word is "elido", which is elide; and an English dictionary will give elide as:

1 to leave out; suppress, omit, or ignore 2 to leave out or slur over (a vowel, syllable, etc.) in pronunciation

Also, elision:

1 the omission, assimilation, or slurring over of a vowel, syllable, etc. in pronunciation...

In the end, with our Roman books, I think it is left to our discretion exactly how this "elision" happens, or not.

I'm often amused at my Angelus Press Daily Missal - as of 1962 - copyright 2004.

Before the Gospel, the deacon asks for the priest's blessing, "Jube, Domne, benedicere."

quite traditional.

Then, on the next page, if no deacon is present, the priest says "Jube, Domine, benedicere."

quite literal.

I don't know if there is logic in this display of elision and no elision.

In the 1912 Antiphonal, some hymns have all their verses written out with notes, and some only have notes for the first verse. The "supervenient" syllables that don't fit the meter are italicized so that when singing a hymn verse that isn't written out, everyone sings together (using the rules below). But when every verse was written out, the appropriate extra note is given for the extra syllables.

While obviously there was pushback (by Solesmes?) and the 1915 decree quoted above gives the option of eliding the syllables, the original rules (Antiphonale Romanum, p. 52*) cited the precedent of the ancient codices for singing every syllable distinctly and gave a system to modify the tune by either adding notes or splitting a note off of an adjacent neume:

1. If there is a hyphen before the italic syllable, sing that syllable on the pitch of the next syllable.

2. If there is no hyphen, sing the italic syllable on the pitch of the previous note.

3. If the is an asterisk ( * ) after the italic syllable, with or without a hyphen, that means a neume (e.g. clivis) precedes or follows, and a note is "split off" for the italic syllable.

(Posting this anyways, even though while I've been writing it, rarty has just posted along the same lines.)

A matter that may bear looking into, to wit, the actual direction from the Vatican Edition of the Antiphonale Romanum (1912), p. 51*:

De syllabis in hymnodia hypermetricis seu supervenientibus.

Quaestio est de syllaba quae excedit numerum metri regularem, ut in seq. versibus: Cum Patre et almo Spiritu - O sola magnarum urbium - Speculator astat desuper. - Juxta usum apud antiquos receptum, talis syllaba etiam in cantu non opprimenda seu elidenda, sed distincte pronuntianda est: et ipsi tribuenda est propria nota, quae aliquando debet esse in eadem chorda ac syllaba praecedens, aliquando in chorda syllabae sequentis reponi: nam pro tali casu regula uniformis non potest proponi, sed solutio pendet ex ipsa hymni melodia.

In Antiphonario, singulis casibus providetur sequenti ratione.

Vocalis syllabae supervenientis scribitur charactere cursivo seu italico, quo facilius secernatur.

In Hymnis qui per singulas strophas cantu instruuntur, pro quavis syllaba hujusmodi scribitur nota conveniens.

Si stropha prima tantum notis instruitur, syllabae supervenienti in hac occurrenti nota propria non superscribitur, ne in cantu aliarum stropharum confusio gignatur. Sed in qua nota reponi debeat, indicatur eodem modo ac in ceteris strophis sine cantu, scilicet per lineolam - quae ante syllabam posita denuntiat illam in sequenti nota esse decantandam. Si vero deest lineola, in praecedenti. Si syllaba superveniens est per se dictio monosyllaba, signum - ante vel post ponitur prout vel praecedenti vel sequenti notae reponenda est.

Si autem ante vel post syllabam supervenientem adest in cantu neuma duarum vel plurium notularum, aliquando fieri potest ut res melius componatur per neumae disjunctionem, scilicet tribuendo praedictae syllabae pro casu seu ultimam praecedentis neumae, seu primam sequentis notulam. Quod per signum * indicantur, syllabae adjunctum.

Haec sedulo observanda sunt a Cantoribus, et etiam a Notatoribus qui Hymnos ex Antiphonario desumptos per singulas strophas cantu adornare vellent.

I don't have time at the moment to translate all this in detail, but the information I'm getting (if I'm not wrong) is roughly thus:

1) According to the received use of the ancients, these syllables are not elided, but rather, they are distinctly pronounced, even in singing. They are given a proper note, which is sometimes the same as the preceding syllable, sometimes as the following. However, there is not a uniform rule; it depends on the melody of the particular hymn.

2) In the Antiphonale, each case is provided for in the following manner.

3) These syllables are always written in italics. (In fact, a good deal of the time, it is only the vowel which is italicized, giving a clue that should you in fact choose to omit it, the consonants should nevertheless remain.)

4) In Hymns for which all the verses are written out, for each of these syllables there is written out a corresponding note.

5) If only the first verse is written out with notation, any extra syllables that may occur in this verse are not given their proper notes (in writing, that is), lest this cause confusion in the following verses. Rather the notes these syllables should be given are indicated in the same manner as in the verses without notation, to wit, by the little line - which, placed before a syllable shows that it should be sung on the same note as the following syllable. However, if there is no little line, it is sung on the same note as the previous syllable. The little line is also used in the case of monosyllables (I am not exactly sure about the possibilities mentioned here for this, but I still think it is meant to signify in a similar manner).

6) However, if there happens to be a neume before or after the extra syllable, sometimes the insertion of the extra syllable is better served by the splitting of the neume, and these cases are indicated by the * sign.

7) These things are to be carefully observed by singers (or cantors), and also by notators (that's me!) who wish to adorn the Hymns from the Antiphonale with notation for all the verses.

Anyhow, this nuanced use of the "little line" or hyphen is rather remarkable.

(With the caveat: It is no doubt very easy to produce typos in the application of this system. In my investigations thus far, I have seem "Cum Patre et" in one place, but "Cum Pa-tre et" in another, for hymns using the same tune.)

I say this may bear looking into, because it would be interesting to see how this system plays out in each individual case in the Antiphonale. I would think it quite possible that this method does indeed show a unique solution for every occurring case. Finally, with this being the only system set forth in the Vatican Edition as originally published, it would be reasonable to say that, strictly speaking, it is the most authentic practice to follow in singing these hymns.

I suppose I should also add that, in practice, my default procedure is to split the splittable neumes, but elide in the other cases.

My guess is that I acquired this habit from modern editions such as the Parish Book of Chant and the SSPX's Traditional Roman Hymnal, which notate in this fashion.

However, although it may be "farby" I have not yet been moved to change this practice, as it is admittably a reasonable / definable method and seems within the bounds indicated by the S.R.C.

Sure, a single method should be agreed to and well rehearsed, but the point is that the meter is not necessarily to be kept-to at the expense of singing each syllable distinctly on a full note.

It seems like a hundred years ago (Antiphonale Romanum) there was an attempt to bring this method back (as the old manuscripts indicated singing an "extra" syllable on a distinct note), but it never caught on — possibly on an aesthetic objection, and maybe just because modern hymns don't work like that. Although I've never heard Adorot devote...