A Dictionary of Music and Musicians/Antiphon
ANTIPHON (from the Greek αντιφωνέω, to raise the voice in reply), a short piece of plainsong introduced before a psalm or canticle, to the Tone of which it corresponds, while the words are selected so as specially to illustrate and enforce the evangelical or prophetic meaning of the text.
The following is the antiphon which opens the service of Lauds (corresponding to the English Morning Prayer) on Easter Day, and supplies the evangelical comment on the Psalm which follows it. The same Psalm is sung at the beginning of Lauds every Sunday, but with a different antiphon, suggesting a different application of its contents.
Psalm 92 ( = 93 Eng. Ps.)
The connection of the music of the antiphon with that of the psalm is explained by Durandus from the etymology of the term—'because antiphons are as keys and indices according to the modulation and sound of which the following canticle or psalm is sung alternately. For the tone of the whole psalm is taken from the tone of the antiphon.'
Antiphonal or alternate singing, as in the chanting of psalms verse by verse—or by half verses, as heard by Mendelssohn in Rome during the Holy Week (see his Letter of June 16, 1831)—is of very high antiquity. It was characteristic of the Hebrew and early Christian worship, and is mentioned by Philo in the middle of the first century, describing the Therapeutse (De Vit. Cont.), and has always been more or less practised in the Church.
The French term 'antienne' and the English 'anthem' are derived from antiphon, probably in reference to each of the meanings given above, as an independent piece of music sung from side to side of the choir.