Magnification and Irmos of the Nativity
The following hymns are sung at the Divine Liturgy in place of "It is truly proper" from the feast of the Nativity (December 25) through the leavetaking of the feast (December 31) - with the exception of the Synaxis of the Theotokos (December 27), which has its own magnification and irmos. These hymns can be found on pages 293-294 of the Divine Liturgies book.
After the priest prays the Epiclesis and the beginning of the commemorations, concluding:
... especially for our holy, most pure, most blessed and glorious Lady, the Theotokos and Ever-Virgin Mary.
the faithful sing the magnification of the feast:
When singing this magnification, PAY ATTENTION to the transition from the end of the first line of music to the start of the second; "Christ the King" does not begin on the same pitch as "soul", but a whole step higher.
The magnification is immediately followed by the irmos of the 9th ode of the feast-day Canon, from Matins:
The irmos begins on the same pitch that ends the magnification.
Note than most irmosy in the Divine Liturgies book are provided in two settings: a "simple" setting which uses the well-known tone 6 irmos melody, and a setting which uses the traditional prostopinije melody for that particular irmos. The feasts of the Nativity, Theophany, and Pascha are the exceptions; all three use eminently "singable" melodies which are easy to learn, and which the Inter-Eparchial Music Commission felt should continue to be heard in our churches.