Mercurial > hg > cip2012
diff draft.tex @ 35:194c7ec7e35d
Re-wrote section IV
author | Henrik Ekeus <hekeus@eecs.qmul.ac.uk> |
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date | Wed, 14 Mar 2012 18:21:16 +0000 |
parents | 25846c37a08a |
children | ec7d64c0ae44 |
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--- a/draft.tex Wed Mar 14 13:17:05 2012 +0000 +++ b/draft.tex Wed Mar 14 18:21:16 2012 +0000 @@ -621,69 +621,46 @@ \section{Information dynamics as compositional aid} -In addition to applying information dynamics to analysis, it is also possible -use this approach in design, such as the composition of musical materials. By -providing a framework for linking information theoretic measures to the control -of generative processes, it becomes possible to steer the output of these processes -to match a criteria defined by these measures. For instance outputs of a -stochastic musical process could be filtered to match constraints defined by a -set of information theoretic measures. +In addition to applying information dynamics to analysis, it is also possible to apply it to the generation of content, such as to the composition of musical materials. +The outputs of algorithmic or stochastic processes can be filtered to match a set of criteria defined in terms of the information dynamics model, this criteria thus becoming a means of interfacing with the generative process. +For instance a stochastic music generating process could be controlled by modifying constraints on its output in terms of predictive information rate or entropy rate. -The use of stochastic processes for the generation of musical material has been -widespread for decades -- Iannis Xenakis applied probabilistic mathematical -models to the creation of musical materials, including to the formulation of a -theory of Markovian Stochastic Music. However we can use information dynamics -measures to explore and interface with such processes at the high and abstract -level of expectation, randomness and predictability. The Melody Triangle is -such a system. +The use of stochastic processes for the composition of musical material has been widespread for decades -- for instance Iannis Xenakis applied probabilistic mathematical models to the creation of musical materials\cite{Xenakis:1992ul}. +Information dynamics can serve as a novel framework for the exploration of the possibilities of such processes at the high and abstract level of expectation, randomness and predictability. \subsection{The Melody Triangle} -The Melody Triangle is an exploratory interface for the discovery of melodic -content, where the input -- positions within a triangle -- directly map to -information theoretic measures associated with the output. -The measures are the entropy rate, redundancy and predictive information rate -of the random process used to generate the sequence of notes. -These are all related to the predictability of the the sequence and as such -address the notions of expectation and surprise in the perception of -music.\emph{self-plagiarised} +The Melody Triangle is an exploratory interface for the discovery of melodic content, where the input -- positions within a triangle -- directly map to information theoretic measures of the output. +The measures -- entropy rate, redundancy and predictive information rate -- form a criteria with which to filter the output of the stochastic processes used to generate sequences of notes. +These measures address notions of expectation and surprise in music, and as such the Melody Triangle is a means of interfacing with a generative process in terms of the predictability of its output. -Before the Melody Triangle can used, it has to be `populated' with possible -parameter values for the melody generators. These are then plotted in a 3d -statistical space of redundancy, entropy rate and predictive information rate. -In our case we generated thousands of transition matrixes, representing first-order -Markov chains, by a random sampling method. In figure \ref{InfoDynEngine} we see -a representation of how these matrixes are distributed in the 3d statistical -space; each one of these points corresponds to a transition -matrix.\emph{self-plagiarised} +The triangle is `populated' with possible parameter values for melody generators. +These are plotted in a 3d statistical space of redundancy, entropy rate and predictive information rate. + In our case we generated thousands of transition matrixes, representing first-order Markov chains, by a random sampling method. + In figure \ref{InfoDynEngine} we see a representation of how these matrixes are distributed in the 3d statistical space; each one of these points corresponds to a transition matrix. + + + + +The distribution of transition matrixes plotted in this space forms an arch shape that is fairly thin. +It thus becomes a reasonable approximation to pretend that it is just a sheet in two dimensions; and so we stretch out this curved arc into a flat triangle. +It is this triangular sheet that is our `Melody Triangle' and forms the interface by which the system is controlled. +Using this interface thus involves a mapping to statistical space; a user selects a position within the triangle, and a corresponding transition matrix is returned. +Figure \ref{TheTriangle} shows how the triangle maps to different measures of redundancy, entropy rate and predictive information rate. -When we look at the distribution of transition matrixes plotted in this space, -we see that it forms an arch shape that is fairly thin. It thus becomes a -reasonable approximation to pretend that it is just a sheet in two dimensions; -and so we stretch out this curved arc into a flat triangle. It is this triangular -sheet that is our `Melody Triangle' and forms the interface by which the system -is controlled. \emph{self-plagiarised} - -When the Melody Triangle is used, regardless of whether it is as a screen based -system, or as an interactive installation, it involves a mapping to this statistical -space. When the user, through the interface, selects a position within the -triangle, the corresponding transition matrix is returned. Figure \ref{TheTriangle} -shows how the triangle maps to different measures of redundancy, entropy rate -and predictive information rate.\emph{self-plagiarised} -Each corner corresponds to three different extremes of predictability and -unpredictability, which could be loosely characterised as `periodicity', `noise' -and `repetition'. Melodies from the `noise' corner have no discernible pattern; -they have high entropy rate, low predictive information rate and low redundancy. -These melodies are essentially totally random. A melody along the `periodicity' -to `repetition' edge are all deterministic loops that get shorter as we approach -the `repetition' corner, until it becomes just one repeating note. It is the -areas in between the extremes that provide the more `interesting' melodies. That -is, those that have some level of unpredictability, but are not completely ran- -dom. Or, conversely, that are predictable, but not entirely so. This triangular -space allows for an intuitive explorationof expectation and surprise in temporal -sequences based on a simple model of how one might guess the next event given -the previous one.\emph{self-plagiarised} + +Each corner corresponds to three different extremes of predictability and unpredictability, which could be loosely characterised as `periodicity', `noise' and `repetition'. +Melodies from the `noise' corner have no discernible pattern; they have high entropy rate, low predictive information rate and low redundancy. +These melodies are essentially totally random. +A melody along the `periodicity' to `repetition' edge are all deterministic loops that get shorter as we approach the `repetition' corner, until it becomes just one repeating note. +It is the areas in between the extremes that provide the more `interesting' melodies. +These melodies have some level of unpredictability, but are not completely random. + Or, conversely, are predictable, but not entirely so. + +The Melody Triangle exists in two incarnations; a standard screen based interface where a user moves tokens in and around a triangle on screen, and a multi-user interactive installation where a Kinect camera tracks individuals in a space and maps their positions in physical space to the triangle. +In the latter visitors entering the installation generates a melody, and could collaborate with their co-visitors to generate musical textures -- a playful yet informative way to explore expectation and surprise in music. +Additionally different gestures could be detected to change the tempo, register, instrumentation and periodicity of the output melody. \begin{figure} \centering @@ -698,43 +675,25 @@ not visible in this plot, it is largely hollow in the middle. \label{InfoDynEngine}} \end{figure} - - - -Any number of interfaces could be developed for the Melody Triangle. We have -developed two; a standard screen based interface where a user moves tokens with -a mouse in and around a triangle on screen, and a multi-user interactive -installation where a Kinect camera tracks individuals in a space and maps their -positions in the space to the triangle. - Each visitor would generate a melody, and could collaborate with their co-visitors - to generate musical textures -- a playful yet informative way to explore - expectation and surprise in music. As a screen based interface the Melody Triangle can serve as composition tool. -A triangle is drawn on the screen, screen space thus mapped to the statistical -space of the Melody Triangle. -A number of round tokens, each representing a melody can be dragged in and -around the triangle. When a token is dragged into the triangle, the system -will start generating the sequence of notes with statistical properties that -correspond to its position in the triangle.\emph{self-plagiarised} +A triangle is drawn on the screen, screen space thus mapped to the statistical space of the Melody Triangle. +A number of round tokens, each representing a melody can be dragged in and around the triangle. +When a token is dragged into the triangle, the system will start generating the sequence of symbols with statistical properties that correspond to the position of the token. +These symbols are then mapped to notes of a scale. + Keyboard input allow for control over additionally parameters. -In this mode, the Melody Triangle can be used as a kind of composition assistant -for the generation of interesting musical textures and melodies. However unlike -other computer aided composition tools or programming environments, here the -composer engages with music on the high and abstract level of expectation, -randomness and predictability.\emph{self-plagiarised} - - -Additionally the Melody Triangle serves as an effective tool for experimental investigations into musical preference and their relationship to the information dynamics models. - - %As the Melody Triangle essentially operates on a stream of symbols, it it is possible to apply the melody triangle to the design of non-sonic content. - \begin{figure} \centering \includegraphics[width=0.9\linewidth]{figs/TheTriangle.pdf} \caption{The Melody Triangle\label{TheTriangle}} \end{figure} +In this mode, the Melody Triangle is a compositional tool. +It can assist a composer in the creation not only of melodies, but by placing multiple tokens in the triangle, the generation of intricate musical textures. +Unlike other computer aided composition tools or programming environments, here the composer engages with music on the high and abstract level of expectation, randomness and predictability. + + \section{Musical Preference and Information Dynamics} We carried out a preliminary study that sought to identify any correlation between aesthetic preference and the information theoretical measures of the Melody