Most of the repertoire of choral music composed since 1950 does not call for the use of conducting techniques relating to this book. It is much more difficult for singers to pitch notes in a chromatically based work than it is for an instrumentalist, whose displacement of fingers automatically produces correct pitches. Most composers demonstrate an awareness of this in avoiding complex pulses and variable time-units. However, there are some vocal works which do require exceptional rehearsal procedures which do not fall within the normal specialist field of choral conductors. Irrational note-groups and their subdivisions within a unit exact tremendous concentration from singers. Such a work is Ligeti’s Lux aeterna for sixteen-part mixed a cappella choir. The following recommendations might be considered by choral and instrumental conductors.

Example 40 shows Ligeti in his familiar crotchet-orientated graphics. None of the sixteen voices articulate their notes at exactly the same time. Unless the displacements are exact the effect of the music will fail. The whole piece is very quiet and calm. Ligeti requests all the voices in the choir to sing totally without accents: ‘bar lines have no rhythmic significance and should not be emphasized’. It is not easy for singers to enter in a subdivided unit on, for instance, the third quintuplet subdivision of a crotchet without making an emphatic articulation. The technique for unaccented articulations must be developed in rehearsal by the person who is to conduct the performance.

There are three issues of technique to be considered:

• 1 The intonation of chromatic intervals in the four parts which are not related to diatonic harmony.

• 2 Unaccentuated articulations in a sustained line.

• 3 Sustaining a consistent pp dynamic in long phrases.

Example 41 is offered as a preparatory exercise, which involve these three characteristics. At first it is helpful if each of the items is practised individually so that aural perception can be formed and established in a concentrated way. As always, repetition will create a habit which can gradually become automatic in application. By practising the chromatic scales in each voice, the non-diatonic relationships in the chords will become familiar territory in the aural reception of the singers.