RESPONSORIUM. – In the Mass, after the reading, and in the Office at the end of each lesson, and at the minor hours after the Chapter, the soloist sings or recites a verse of the psalm or a passage of Sacred Scripture to which the choir responds.
The first and second are called r. prolixum, the rest r. breve. Its origin lies in the need to allow the readers to rest between one passage and another and also to provide a little variety in the liturgical service. The r. is indicated by the letter R and is divided by an asterisk into two or three sections, one of which is called Repetuando, and by a versus, sometimes more than one, with the concluding doxology of the Gloria Patri in the last r. of each Nocturn and in every short r., except during Passiontide. In the Office of the Dead, the Requiem is used in its place.
The manner in which responsorial psalmody was sung in the first centuries, when it was introduced, is not known. On the basis of an allusion by St. Augustine, one may suppose that the soloist’s verses and the choir’s response were performed on recitatives and melodies much simpler than the singing of our short r. and of the present invitatories. Later, almost all the melodies would become more ornate and the number of verses consequently reduced, so that in medieval codices it is very rare to find an r. of more than one verse. In present usage this latter form is found only in the r. Aspiciens a longe and Libera.
Among the various musical forms deriving from ancient responsorial psalmody, only three have retained the name r. One occurs in the first part of the Mass: it is the gradual r., whose structure has been altered by the suppression of the refrain after the verse. The melody of the verse is very highly developed: constructed almost always on a scale higher than that of the first part of the r., it offered the soloist the opportunity to perform his part with great virtuosity. The gradual r.’s were composed or centonized preferably in the fa mode, a fact deserving particular attention, since this was the mode exploited in all the other genres of Gregorian music.
The other two forms of r. are found in the Office: the short r.’s, performed on very simple melodies, and the long ones, which are often also composed of formulas, but in a more varied and ornate style. The latter, unlike the gradual r.’s, have stereotyped verses comprising two parts with intonation, tenor, and cadence; they are fixed in eight melodic schemes corresponding to the eight psalm tones. This regularity later came to seem tedious, and composers modified the rule with exceptions that became increasingly frequent. From the tenth century onward, the r.’s, written for the most part in the re mode, each have their own verse. Another element of variety derives from a long melisma which, in the most celebrated medieval r.’s, adorns one of the final words and gives rise to a brief prose. Thus, for example, Inviolata and Sospitati were added to the r. Gaude Maria Virgo, and Ex eius tumba to the r. d.i.s. Nicola. The systematic search for assonances in a in Inviolata, and in e and o in Sospitati, is a law of the genre: the aim was to prolong as much as possible the timbre of the vowel over which the original melisma rose.