Monteverdi’s Setting of the Psalm Lauda Ierusalem (1610)
A nearly continuous psalm tone cantus firmus (tone 3 with finalis a) in the the tenor voice forms the scaffolding for Lauda Ierusalem. In the first two verses the chant begins with the intonation, but in subsequent verses it follows the normal pattern of commencing with the reciting note. Transposition of the psalm tone by a fourth occurs in verses 4-6 and again at the beginning of the doxology. Within the tonal areas prescribed by the reciting level of the chant, the harmony fluctuates continually, never establishing a regular pattern.
Lauda Ierusalem, like Nisi Dominus, is characterized by two choirs in frequent antiphonal responses, but the texture is thinner, comprising only seven parts. The six voices apart from the cantus firmus are subdivided into two equal ensembles of canto, alto, and bass, and the more transparent sonority of these three-voice choirs facilitates more frequent interchanges and greater rhythmic complexity than is exhibited by Nisi Dominus. While the overall tonal organization of the psalm is determined by the pitch at which the reciting note appears, structure on a smaller scale is determined, as in Nisi Dominus , by antiphony. However, in contrast to the lengthy passages with one choir only that characterize Nisi Dominus, the second choir of Lauda Ierusalem regularly alternates (sometimes in imitation) with the first choir at the interval of approximately three bars.
With verse 5 this interval is reduced by at least half. Finally the two choirs join in verse 7, at the point where the chant returns its original reciting level, and remain together until the doxology. Although the texture in verse 7-9 is full-voiced and mostly homophonic, it is simultaneously imitative (sometimes only in the outer voices). At verse 9 the time between entries reduces to only a half or quarter note (depending on the voice), producing a lively mosaic of entrances as pitches and mtifs heard in the leading trio reappear almost immediately in the other while the tenor continues to intone the cantus firmus uninterruptedly. I know of no other example of doubl-choir music from this period, aside from the first and last verses of Montecerdi’s Nisi Dominus, that develops such a complex texture from the interplay of two separate groups.
Like Nisi Dominus, the doxology is anentirely separate section where the chant for the first time migrates out of the tenor into the top voice, achieving greater prominence. The Sicut erat, which in this case does not resemble the opening verse, begins with rhythmisized falso bordone, followed by an imitative texture based entirely on the psalm tone. Because the psalm tone comprises principally a repeated pitch, this imitative texture differs from the rhythmicized falso bordone in its straggered entrances. In contrast to Nisi Dominus, a large polyphonic Amen, from which the cantus firmus is absent, concludes Lauda Ierusalem. The structural parralels between Lauda Ierusalem and Nisi Dominus not only relate these two psalms to one another, but separate them from the other three, which are also related to one another by various means.
[Excerpted from The Monteverdi Vespers of 1610: Music, Context, Performance by Jeffrey Kurtzman. Oxford and New York: Oxford University Press, 1999, pp 208-211.]