Alleluias in Modes 4, 5, 6, 7
Alleluia is sung at Mass with a melismatic extension on “-ia,” called the iubilus or song of jubilation. There is a verse section, with words usually from a Psalm, similar to the Psalm verse at the Introit, but sung with a much more elaborate melody. The melodic tone throughout the Alleluia and verse varies greatly from one Alleluia to another, with differences in tone from bright and festive, to solemn yet still festive, to a quality—peculiar to Gregorian chant—of musing with dark inner elation.
Abbreviated references here include the following: Ps. 46:6 means that the verse is from verse 6 of Psalm 46.
“GT236” gives the page reference to Graduale triplex. “M102” = Mass formulary 1 in Hesbert’s Antiphonale missarum sextuplex.