The instrument is meant to be the one calling for the last judgement, as mentioned in the Epistle reading.

In the Divine Liturgy, the prokeimenon always precedes the Epistle reading, after the singing of the Trisagion.

Then the royal couple retired to a tented enclosure where they were robed in royal attire, returning to hear a sermon, the Kyrie and Gloria, and then a prayer and the Epistle reading.

The rite of proclamation, the Epistle readings and Gospel are chanted by the Priest, Deacons, and Readers.

The Epistle reading is announced and read.

Part II talks about the duties of those who follow God's invitation, to pass the love of Christ in order to achieve heaven on earth, a thought also expressed in the Epistle reading.

In the Divine Liturgy of the Eastern Orthodox Church and the Byzantine Rite Catholics the Epistle reading is called the Apostol (the same name is given to the lectionary from which it is read).

These daily Epistle readings are a part of the Paschal cycle, being ultimately dependent upon the date of Pascha (Easter).

The Epistle reading is always linked to a reading from the Gospel, though some services, such as Matins, will have a Gospel lesson, but no Epistle.

-the "Apostle" is the usual ancient Eastern title for the Epistle reading, and the "Prologue of the Alleluia" would seem to be a prayer or verse before Alleluia was sung by the choir.