I'm trying to decipher this text, or find at least part of a sentence so I can find the complete text online. I believe it's Latin, but stand to be corrected. The primary reason is I wanted to see if there is a recording of this. I suspect it's Gregorian chant, and I looked through a lot of such lyrics but couldn't find text that looks similar in any of the books I had.
The text says:
Trinum deum et unum pronis men-
tibus adoremus virginique matri
gratulantibus animis iugiter iubilemus.
Venite exultemus domino iubilemus de-
o salutari nostro praeoccupemus faciem e-
ius in confessione et in psalmis iubilemus
ei. Quoniam deus magnus dominus
et rex magnus super omnes deos quoniam
I failed to find this specific text anywhere, but it certainly looks like some kind of a chant with elements pulled from the Psalms. The individual parts starting with capital letters might have different origins. Perhaps someone else can point you to the source(s).
Lines 4 and following are Psalm 94. As to lines 1–3, I believe what we have is an example of an antiphon, where a bit of chant that is extraneous to a psalm precedes, follows, and sometimes (I believe) is also repeated between the verses of that psalm. Specifically, this should be an example of an invitatory, since it uses Psalm 94. The details from the courses in early music that I took as an undergrad are a bit sketchy, unfortunately, but I just found this nice-looking illustrated guide.
In addition to the above answers, the following may provide some further background to your text.
Following the trail to Trinity College, Dublin, I found the text online. The caption reads (in part): "This manuscript was created for the Order of the Most Holy Saviour, also known as the Bridgettines, a monastic order of Augustinian nuns." It dates from the 15th century, second half. You can see it (and the rest of the exhibition) here.
The anitphon (lines 1-3) seems to be unusual, even perhaps unique to this order, because all my Googling of it kept taking me back to them and to a book called "Myroure of Our Ladye", a book of instructions for the nuns. I mention this because you said you wanted to find a recording. But while the Venite/Psalm 94 itself is widely recorded, I couldn't find versions with this antiphon. But now we know the specific order that used this psalter, perhaps you could find it.