Engineering and Music
"Human Supervision and Control in Engineering and Music"

Orchestra Concert
Ensemble Concert
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Anja Fleischer
"Human Supervision and Control in Music"

The Supervisory function of a conductor is a special case of controlling the cooperation of partly autonomous agents. To understand the different types of the orchestra’s internal organization, an analysis of the score is one of the basic requirements, since they depend on the interrelations between the different layers of the musical structure.
Position Statement
The Supervisory function of a conductor is a very special case of controlling the cooperation of partly autonomous agents. Orchestra musicians are extremely high skilled agents, who have passed years of education, mostly beginning in childhood,  not only in order to grasp their instrument technically, but also to study the different requirements of various music styles regarding a musically  competent interpretation. The common starting point for both the conductor and the orchestra musicians is the score, the rehearsal aims at a performance of this underlying score.  In this way a transformation process from the symbolic reality of the signs of the score into the physical reality of sounds takes place. The description of  the supervisory control of the conductor as well as the interaction of the partly autonomous musicians therefore is first of all in need of a description of this transformation process. 

The common rehearsal is by no means the starting point of this transformation process. To perform a piece of music is not a question of a simple reading of  single notes with pitch, onset, duration … and translating it into a sequence of physical sounds. The odd machine interpretation of representations of the score (e.g. MIDI) demonstrated at least, that the transformation process is much more complex. It requires a deep understanding of the mutual relations of the single  elements of  the score  in order to express the very complex nature of the structure of a piece of music within the performance. The conductor as well as the musicians develop their mental imagination of the piece in preparation of the rehearsal while studying the score. Even if a musician has no information about the complete musical work, he gets a certain kind of information by studying his own voice. In this way the orchestra is much more than a mechanical instrument, to which the conductor just  transports his instructions. Claudio Abbado is famous for listening a long time during the rehearsals to what the orchestra offers him until he starts to work upon this offer by advising refinements of interpretation. Understanding the supervisory task of the conductor within the rehearsal or the concert presupposes the  understanding of the different layers of the conductor’s and musician’s knowledge and perspectives concerning the piece of music. In any case the conductor has the controlling function, but the process of developing an interpretation of the piece during a rehearsal can be a mutual enrichment of different perspectives. 

The concrete realization of the conductor’s supervisory control as well as the interaction within the team-play depend on different factors. By no means the conductor is able to guide any kind of the cooperation between the subgroups.  Listening and responding to each other while playing is one of the demands in coordinating the tuning, which is a kind of interaction between the musicians. On the other hand this interaction is in need of a feedback by and the control of the conductor in those cases, where a certain complexity of mutual responding is exceeded. This complexity furthermore depends on a high degree on the complexity of the mutual relations of different voices within the score, from which the complete piece evolves. Different types  of the orchestra’s internal organization are due to different types of the interrelations between the different layers of the musical structure of the piece. Hence an analysis of this structure is one of the basic requirements in order to understand the specific type of controlling processes taking place in a rehearsal. To describe the transformation process of  detecting the structure of the score into playing an expressive performance is the logical next step, which refers to a tradition within the history of performance theory to describe the performer’s task as to elucidate the structure of a piece of music to the audience, to communicate his understanding of the piece, as it is proposed, for instance,  by Hugo Riemann and Theodor W. Adorno. 

In describing the very diverse types of interaction of different voices within a complete piece of music the model of Metrical Coherence is a useful tool concerning the understanding of metrical organization, which was formulated as the outcome of an intensive explorative work with the metric weights of the RUBATO-Workstation for Musical Analysis and Performance. Diverse types of interaction include relatively autonomous forms such as leading voices and accompaniment or different voices of a fugue. (In the special case of tempo rubato an autonomous shaping of timing takes places, where the performance of the melody does not coincides in every point with the corresponding notes of the accompaniment.) Metrical Coherence, which describes the relationship between the inner metrical structure of the notes and the outer meter of the measures and barlines, enables us to detect complex and hidden structures of the metrical interplay between different voices. 

The analysis of the Choir-Fugue of the Credo of Bach’s B-Minor-Mass, for instance, resulted in metrical weights of little regularity for the separate voices (Figure 1). Moreover, these little regularities differed in their accent hierarchy for the diverse voices, which often did not correspond to the given accent hierarchy of the tactus. Considering the whole composition (Figure 2), the outcome of the metric analysis demonstrated a regularity of much higher degree, which even showed a clear correspondence to the given accent hierarchy of the 4/2 meter:  first and third beat of the measure get the highest metrical weight. A singer, knowing only his own voice without information about the complete piece when coming to the rehearsal, might get lost without a help for orientation, since he is now part of a structural design of the complete piece, which was not detected in his separate voice, it evolves only within the interplay of different voices. 

Figure 1: Metric weight of the Bass of the Credo-Fugue.

Figure 1: Metric weight of the Bass of the Credo-Fugue. As higher the streak, as higher the weight, gray lines in the background mark the barlines

Figure 2: Metric weight of the complete Credo-Fugue

Figure 2: Metric weight of the complete Credo-Fugue

Another case of interaction is the metric design of the Confiteor-Fugue of the same mass. The analysis of the separate voices resulted in little regularities as well, but in this case the same regularities could be observed in each voice. Furthermore the analysis of the whole piece detected a higher regularity than the analysis of the separate voices, but the hierarchy within the layers of high and low metrical weights is the same as in the regularities of the separate voices. In this case, a singer having studied only his voice, finds at least some traces of the metrical design of the complete piece in his respective part and might be less surprised in the first rehearsal. 

The symphonies by Johannes Brahms are famous examples for rhythmic-metric ambiguities, which become apparent throughout the comprehension of the metric structure of separate voices, groups of instruments and the complete work. In many cases the metric weights of diverse voices  differ in their regularities in a high  manner, sometimes they interact complementary in such a way, that the analysis of the whole composition results in a metric weight with a lack of any clear differentiation. In this case, it could be difficult for the musician, to play his own part while in the same time giving full attention to the complementary voices, that act on their own structural design.