5.3 Conducting Aleatoric Music
Aleatoric or indeterminate music can present challenges for conductors and may require unconventional approaches to controlling the ensemble. The conductor may be required to give a series of signals at certain landmarks in the piece, separated by a specified duration of time, or co-ordination with one specific instrumental part or gesture. Often there is a system of notation with different symbols to denote the use of both hands or just one hand. A quick glance at most scores by Witold Lutoslawski will give a good example.
In this excerpt from Lincolnshire Posy, Percy Grainger asks the musicians to play together at the notated pitch and (in his own inimitable way) gives detailed information about dynamics, articulation and character. However, the pulse should be free.
Note how the conductor gives a succession of downbeats, only using a pattern for the notes grouped within a triplet. The technique here is to stop at the bottom of each downbeat: that is what enables the pulse to be free, and in fact permits a different interpretation every time. As soon as the beat lifts, the players expect the next beat to follow, so a rebound would prevent the conductor from maintaining both control and flexibility. By stopping at the bottom of the beat, nobody will go on until the movement restarts.
This is a fantastic example of where verbal explanations are likely only to confuse matters. With the correct technique, the only thing that might need to be discussed is the dotted rhythm within the triplet. Everything else will be clear if the correct technique is mastered.