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Rehearsal Analysis of
Indeterminate Music
∗
Gordon Lamb
This work is produced by OpenStax-CNX and licensed under the
Creative Commons Attribution License 2.0
†
Abstract
This module represents a discussion of the analysis of a choral work containing indeterminate (also
called aleatoric or chance), compositional techniques. Examples are used to demonstrate some rehearsal
techniques that can be adapted to other similar musical compositions.
1 REHEARSAL ANALYSIS OF INDETERMINATE MUSIC
Indeterminate music (also referred to as aleatoric or chance music) refers to that which is unpredictable
before a performance. Until the performance a conductor will not know exactly how the piece will sound.
He will have an understanding of the overall sound of the work but not of its individual sounds. Most works
that include indeterminacy are not totally indeterminate. They will contain sections that are completely
predictable and carefully notated, and those that are not. They may also contain sections that range
anywhere between these extremes.
Indeterminate music requires a new kind of analysis and a dierent rehearsal approach than traditional
repertoire. Conductors are required to use their musical imagination more in the study of these scores
because one cannot "play the notes" or visually see the texture, range, harmonic coloring, etc., since the
score may consist of only written instructions or nontraditional notation. A conductor will have to read the
instructions carefully and, based on his own experimentation and his knowledge of vocal sounds, predict the
overall sound.
There is no sure way to predict how each new indeterminate work or section of a work will sound. The
most predictable method is simply from experience. After a conductor has conducted several indeterminate
scores, he can begin to identify certain characteristics of new works that are similar to those encountered
before and more successfully predict the sound of the work.
It is usually impossible to sight-read indeterminate music in the manner of traditional sight-reading.
Often, a conductor should prepare a short talk, including his own demonstration, about the music. Nothing
will be accomplished by asking the singers to "read" the score unless they have an understanding of it. It is
best to nd a section of the work that is the most accessible and rehearse it rst. The singers will be able to
more clearly accomplish the composer's intentions and can better appreciate the sound that will be achieved
when the work is fully prepared.
For example, a passage like that in gure 1 would be a good one to extract from a work as a beginning
to its rehearsal.
∗ Version
1.1: Mar 10, 2009 3:56 pm -0500
† http://creativecommons.org/licenses/by/2.0/
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The composer has indicated a unison C, which is then expanded to a range of approximately two and a
half octaves. There should be no glissando. If a composer desired a glissando, he would usually use a wavy
line between notes to indicate it. Only a straight line is used here. This eect is sharper and has more force
than a glissando. Singers are allowed to choose any notes between and including the notated B-at and E.
The conductor will need to assign several voices to the two notated pitches and then ask the other singers
to ll in the sounds between those two notes. At rst singers will tend to bunch the pitches; that is, not
uniformly lling in between the two notes. The conductor may have to select some voices for certain ranges
to get a uniform cluster.
Figure 1
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Figure 2
Other passages of indeterminate music are not as easily rehearsed. Often, composers use graphics to
represent sound goals or sound ideals to the singer. The graphics in gure 2 are taken from Barney Childs's
Variations written for chorus, tape, and bells. Obviously, there is considerable room for individual interpretation. Some singers will nd it very hard to respond to these symbols, and a conductor will need to lead
inexperienced singers carefully into the repertoire. A conductor can demonstrate, providing a model for the
singers.
The technique below, in gure 3, is one that is often used. It requires an explanation from the conductor
and, as with similar techniques, experimentation from the singers. Singers are to sing any circle and proceed
to the next circle connected by a line. Singers should divide and begin so all circles are sung at the same
time. Only the singers who begin on the upper left circle may sing the text in syllabic order. The composite
sound will still resemble "Kyrie" for the audience, although it will be fragmented.
Only after several attempts will singers begin to feel comfortable with these sections. After many rehearsals, such passages may begin to sound the same every time because the singers will forget to be original
in their choices, and simply sing it the same way each time. If this is the case, the spontaneity of the passage
is lost. The conductor must not allow this to happen. He must encourage experimentation each time, and
must not overrehearse such a passage.
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Figure 3
It is most important for the conductor to totally understand indeterminate scores before presenting the
work to the choir. He will most likely "talk" the ensemble through the work, explaining the intent and type
of sound expected. He can also describe how continuity is achieved in the work and how the parts relate to
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each other.
It should be emphasized that conductors must study the score carefully, anticipating diculties that may
arise for the singers. Every conductor must remember, however, that even with one's own choir, an attempt
to determine which characteristics of a piece will need the most attention is a gamble. The conductor's
gamble is based on his experience with voices, with people, and with his own choir. There will be times
when anticipated problems do not occur and when others, not anticipated, do occur. The conductor must
be able to recognize when he has miscalculated and be exible enough to change direction, responding to
the immediate needs of the choir rather than to his rehearsal plan.
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