The homepage of the "A Song for Bayes" arrangment

The homepage of the choir vox11 including music samples

Bayesian music - an introduction


To the composer, Kristian Echwald Melchiorsen, Bayesian net is not a primitive excuse for composing and performing choir pieces. To Kristian, Bayesian net is an interesting challenge as inspirational source because


  1. The propagation in a bayesian net could be a way to organise how choir sing with each other. The idea of propagation could be compared to Circle Songs, which a number of acappala choirs sing. An. example of a Circle song is here given by Bobby McFerrin who sings "Circle Songs no. 6"

    Which compositions based on bayes net propagation give.

  2. Bayesian nets open up a new range of performance possibilities. Among them is the option of giving the audience some influence over how the music is being performed. Modern rhythmic vocal groups such as Vox11 are used to performing as an "intelligent choir" - that is, each singer is able to solve technical issues without the aid of a conductor. The conductor therefore changes role and makes decisions concerning the whole group - decisions such as how the sound should be, which vocals should be sung, which voices should sing etc. These decisions are usually made spontaneously by the conductor, using his creative and musical abilities. Using bayesian nets, it becomes possible to extend the decision-making process to all participants - the composer, the singers and even the audience, thus maybe (the result of the experiment will tell) creating "the intelligent performance".

    Can bayes net give formal rules that can guide an "intelligent choir"?

Kristian Melchior Echwald is philosopher, matematician, head of 2-3 choirs and composer.  He says "A Song for Bayes" is a interesting challenge.







Initially the people around Kristian, that is Morten Aagaard and Finn V. Jensen did not have more that these visions. The conceptualisation and composition and has taken place through 4 stages. 


No What Time period
1 Concept: an idea/phenonma, that can be modelled. August-September 2011
2 Sketch of bayesian net that can can be foundation September-November 2011
3 Composers first draft of all music pieces were composed. Could be played in "Sibilius" and reviewed(seen and heard) by bayesians. December 2011
4 Composer and choir learns the pieces. A certain artistic "freedom" was given January-February -2012

Stages in in which the core idea - strong integration of bayes net in the composition was maintained. 

After stage 3 a "Bayes net - piece book" was published. Version 1.0 is available here. It should be stressed that it is version 1.0 due to the fact that the choir and conductor is learning the pieces right now. 


In this challenging interdisciplinary collaboration the composition process was guided by one single vision.

Because of the evidently difficulties in understanding each others minds and ideas and (not least) because the composer and choir needed a artistic freedom. 

The simple vision has been that 

"The music should reflect the beauty of bayes net formalism"

The contrary example was Schönbergs 12 tone music, which is music that is rooted in some music theoretical considerations that theoretical nice, but sounds wise the results are less attractive. An youtube example of Schönbergs can be found here: Arnold Schoenberg's Twelve-Tone Method.("Three Piano Pieces, No. 1")


For the same reason the opportunity to play the composed music by electronic equipment was rejected initially. It would make the tunes sound mechanical and the opportunity to audialise the  analog() propabililties seemed more difficult. The choir, Vox11, which have accepted the challlenge is a very professional and experimental choir rooted in a harmonical tradition. One of Vox11s presentation videos are here. More samples of the skills and sound can be found on Vox11' webpage. (in danish)

To handle the contradiction between the demand to use bayes net and artistic freedom the concert is organised in three movements

1.movement -  labeled "Pedagogical"

2. movement labeled "Creative"

3. movement labeled "Synthesis"


In this way the result, the pieces sung at "A Song for Bayes" is based on the beauty of bayes net formalised and and interdisciplinary collaboration founded on a simple clear vision and a lot of trust to participants in the project.