If you search for 'Antiphon' on this blog you will find several references to these Advent antiphons in years go by.
It looks as though I first came across them in 2011, thanks to the ibenedictines.org blog post here where Sister Catherine Wybourne explains what they are and where they fit into the Advent liturgy.
You can also find the texts in Latin and English, and links to the music at www.themathesontrust.org website here. This site also gives the scripture passages from the Old Testatement book of Isaiah from which the antiphons come.
As I posted earlier, I am a member of a group - two groups now (!) - which meet on zoom to listen to the antiphons, read the text and the Isaiah verses, and spend time thinking about them to see what comes to mind. I am finding these weekly sessions illuminating, and also restful, and calming, and a time to feel more and more expectant about the coming of Advent.
We have been taking one antiphon per week, and will finish jst before the fourth Sunday in Advent. The usual liturgical practice is to sing one every evening in the seven days before Christmas Eve.
I'll finish with an extract from ibenedictines;