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date Thu, 15 Mar 2012 12:14:59 +0000
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700 bar lengths) and phases (\ie positions within a bar). 700 bar lengths) and phases (\ie positions within a bar).
701 } 701 }
702 \end{fig} 702 \end{fig}
703 703
704 \subsection{Content analysis/Sound Categorisation}. 704 \subsection{Content analysis/Sound Categorisation}.
705 Using analogous definitions of differential entropy, the methods outlined in the previous section are equally applicable to continuous random variables. In the case of music, where expressive properties such as dynamics, tempo, timing and timbre are readily quantified on a continuous scale, the information dynamic framework thus may also be considered. 705 Using analogous definitions of differential entropy, the methods outlined
706 706 in the previous section are equally applicable to continuous random variables.
707 In \cite{Dubnov2006}, Dubnov considers the class of stationary Gaussian processes. For such processes, the entropy rate may be obtained analytically from the power spectral density of the signal, allowing the multi-information rate to be subsequently obtained. Local stationarity is assumed, which may be achieved by windowing or change point detection \cite{Dubnov2008}. %TODO mention non-gaussian processes extension 707 In the case of music, where expressive properties such as dynamics, tempo,
708 Similarly, the predictive information rate may be computed using a Gaussian linear formulation CITE. In this view, the PIR is a function of the correlation between random innovations supplied to the stochastic process. 708 timing and timbre are readily quantified on a continuous scale, the information
709 %Dubnov, MacAdams, Reynolds (2006) 709 dynamic framework thus may also be considered.
710 %Bailes and Dean (2009) 710
711 In \cite{Dubnov2006}, Dubnov considers the class of stationary Gaussian
712 processes. For such processes, the entropy rate may be obtained analytically
713 from the power spectral density of the signal, allowing the multi-information
714 rate to be subsequently obtained. Local stationarity is assumed, which may
715 be achieved by windowing or change point detection \cite{Dubnov2008}. %TODO
716 mention non-gaussian processes extension Similarly, the predictive information
717 rate may be computed using a Gaussian linear formulation CITE. In this view,
718 the PIR is a function of the correlation between random innovations supplied
719 to the stochastic process. %Dubnov, MacAdams, Reynolds (2006) %Bailes and
720 Dean (2009)
711 721
712 \begin{itemize} 722 \begin{itemize}
713 \item Continuous domain information 723 \item Continuous domain information
714 \item Audio based music expectation modelling 724 \item Audio based music expectation modelling
715 \item Proposed model for Gaussian processes 725 \item Proposed model for Gaussian processes
716 \end{itemize} 726 \end{itemize}
717 \emph{Peter}
718 727
719 728
720 \subsection{Beat Tracking} 729 \subsection{Beat Tracking}
721 \emph{Andrew}
722 730
723 731
724 \section{Information dynamics as compositional aid} 732 \section{Information dynamics as compositional aid}
725 733
726 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. 734 In addition to applying information dynamics to analysis, it is also possible
727 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. 735 to apply it to the generation of content, such as to the composition of musical
728 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. 736 materials. The outputs of algorithmic or stochastic processes can be filtered
729 737 to match a set of criteria defined in terms of the information dynamics model,
730 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}. 738 this criteria thus becoming a means of interfacing with the generative process.
731 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. 739 For instance a stochastic music generating process could be controlled by modifying
740 constraints on its output in terms of predictive information rate or entropy
741 rate.
742
743 The use of stochastic processes for the composition of musical material has been
744 widespread for decades---for instance Iannis Xenakis applied probabilistic
745 mathematical models to the creation of musical materials\cite{Xenakis:1992ul}.
746 Information dynamics can serve as a novel framework for the exploration of the
747 possibilities of such processes at the high and abstract level of expectation,
748 randomness and predictability.
732 749
733 \subsection{The Melody Triangle} 750 \subsection{The Melody Triangle}
734 751
735 \begin{figure} 752 \begin{figure}
736 \centering 753 \centering
744 and redundancy, and that the distribution as a whole makes a curved triangle. Although 761 and redundancy, and that the distribution as a whole makes a curved triangle. Although
745 not visible in this plot, it is largely hollow in the middle. 762 not visible in this plot, it is largely hollow in the middle.
746 \label{InfoDynEngine}} 763 \label{InfoDynEngine}}
747 \end{figure} 764 \end{figure}
748 765
749 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. 766 The Melody Triangle is an exploratory interface for the discovery of melodic
750 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. 767 content, where the input---positions within a triangle---directly map to information
751 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. 768 theoretic measures of the output. The measures---entropy rate, redundancy and
752 769 predictive information rate---form a criteria with which to filter the output
753 The triangle is `populated' with possible parameter values for melody generators. 770 of the stochastic processes used to generate sequences of notes. These measures
754 These are plotted in a 3d statistical space of redundancy, entropy rate and predictive information rate. 771 address notions of expectation and surprise in music, and as such the Melody
755 In our case we generated thousands of transition matrixes, representing first-order Markov chains, by a random sampling method. 772 Triangle is a means of interfacing with a generative process in terms of the
756 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. 773 predictability of its output.
757 774
758 775 The triangle is `populated' with possible parameter values for melody generators.
759 776 These are plotted in a 3d statistical space of redundancy, entropy rate and
777 predictive information rate.
778 In our case we generated thousands of transition matrixes, representing first-order
779 Markov chains, by a random sampling method. In figure \ref{InfoDynEngine} we
780 see a representation of how these matrixes are distributed in the 3d statistical
781 space; each one of these points corresponds to a transition matrix.
782
783 The distribution of transition matrixes plotted in this space forms an arch shape
784 that is fairly thin. It thus becomes a reasonable approximation to pretend that
785 it is just a sheet in two dimensions; and so we stretch out this curved arc into
786 a flat triangle. It is this triangular sheet that is our `Melody Triangle' and
787 forms the interface by which the system is controlled. Using this interface
788 thus involves a mapping to statistical space; a user selects a position within
789 the triangle, and a corresponding transition matrix is returned. Figure
790 \ref{TheTriangle} shows how the triangle maps to different measures of redundancy,
791 entropy rate and predictive information rate.
760 792
761 The distribution of transition matrixes plotted in this space forms an arch shape that is fairly thin. 793
762 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. 794 Each corner corresponds to three different extremes of predictability and
763 It is this triangular sheet that is our `Melody Triangle' and forms the interface by which the system is controlled. 795 unpredictability, which could be loosely characterised as `periodicity', `noise'
764 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. 796 and `repetition'. Melodies from the `noise' corner have no discernible pattern;
765 Figure \ref{TheTriangle} shows how the triangle maps to different measures of redundancy, entropy rate and predictive information rate. 797 they have high entropy rate, low predictive information rate and low redundancy.
766 798 These melodies are essentially totally random. A melody along the `periodicity'
767 799 to `repetition' edge are all deterministic loops that get shorter as we approach
768 800 the `repetition' corner, until it becomes just one repeating note. It is the
769 801 areas in between the extremes that provide the more `interesting' melodies.
770 Each corner corresponds to three different extremes of predictability and unpredictability, which could be loosely characterised as `periodicity', `noise' and `repetition'. 802 These melodies have some level of unpredictability, but are not completely random.
771 Melodies from the `noise' corner have no discernible pattern; they have high entropy rate, low predictive information rate and low redundancy. 803 Or, conversely, are predictable, but not entirely so.
772 These melodies are essentially totally random.
773 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.
774 It is the areas in between the extremes that provide the more `interesting' melodies.
775 These melodies have some level of unpredictability, but are not completely random.
776 Or, conversely, are predictable, but not entirely so.
777 804
778 \begin{figure} 805 \begin{figure}
779 \centering 806 \centering
780 \includegraphics[width=0.9\linewidth]{figs/TheTriangle.pdf} 807 \includegraphics[width=0.9\linewidth]{figs/TheTriangle.pdf}
781 \caption{The Melody Triangle\label{TheTriangle}} 808 \caption{The Melody Triangle\label{TheTriangle}}
782 \end{figure} 809 \end{figure}
783 810
784 811
785 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. 812 The Melody Triangle exists in two incarnations; a standard screen based interface
786 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. 813 where a user moves tokens in and around a triangle on screen, and a multi-user
787 Additionally different gestures could be detected to change the tempo, register, instrumentation and periodicity of the output melody. 814 interactive installation where a Kinect camera tracks individuals in a space and
815 maps their positions in physical space to the triangle. In the latter visitors
816 entering the installation generates a melody, and could collaborate with their
817 co-visitors to generate musical textures---a playful yet informative way to
818 explore expectation and surprise in music. Additionally different gestures could
819 be detected to change the tempo, register, instrumentation and periodicity of
820 the output melody.
788 821
789 As a screen based interface the Melody Triangle can serve as composition tool. 822 As a screen based interface the Melody Triangle can serve as composition tool.
790 A triangle is drawn on the screen, screen space thus mapped to the statistical space of the Melody Triangle. 823 A triangle is drawn on the screen, screen space thus mapped to the statistical
791 A number of round tokens, each representing a melody can be dragged in and around the triangle. 824 space of the Melody Triangle. A number of round tokens, each representing a
792 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. 825 melody can be dragged in and around the triangle. When a token is dragged into
793 These symbols are then mapped to notes of a scale. 826 the triangle, the system will start generating the sequence of symbols with
794 Keyboard input allow for control over additionally parameters. 827 statistical properties that correspond to the position of the token. These
795 828 symbols are then mapped to notes of a scale.
796 The Melody Triangle is can assist a composer in the creation not only of melodies, but, by placing multiple tokens in the triangle, can generate intricate musical textures. 829 Keyboard input allow for control over additionally parameters.
797 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. 830
831 The Melody Triangle is can assist a composer in the creation not only of melodies,
832 but, by placing multiple tokens in the triangle, can generate intricate musical
833 textures. Unlike other computer aided composition tools or programming
834 environments, here the composer engages with music on the high and abstract level
835 of expectation, randomness and predictability.
798 836
799 837
800 838
801 \subsection{Information Dynamics as Evaluative Feedback Mechanism} 839 \subsection{Information Dynamics as Evaluative Feedback Mechanism}
802 %NOT SURE THIS SHOULD BE HERE AT ALL..? 840 %NOT SURE THIS SHOULD BE HERE AT ALL..?
803 841
804 842
805 Information measures on a stream of symbols can form a feedback mechanism; a rudamentary `critic' of sorts. 843 Information measures on a stream of symbols can form a feedback mechanism; a
806 For instance symbol by symbol measure of predictive information rate, entropy rate and redundancy could tell us if a stream of symbols is currently `boring', either because it is too repetitive, or because it is too chaotic. 844 rudamentary `critic' of sorts. For instance symbol by symbol measure of predictive
807 Such feedback would be oblivious to more long term and large scale structures, but it nonetheless could be provide a composer valuable insight on the short term properties of a work. 845 information rate, entropy rate and redundancy could tell us if a stream of symbols
808 This could not only be used for the evaluation of pre-composed streams of symbols, but could also provide real-time feedback in an improvisatory setup. 846 is currently `boring', either because it is too repetitive, or because it is too
847 chaotic. Such feedback would be oblivious to more long term and large scale
848 structures, but it nonetheless could be provide a composer valuable insight on
849 the short term properties of a work. This could not only be used for the
850 evaluation of pre-composed streams of symbols, but could also provide real-time
851 feedback in an improvisatory setup.
809 852
810 \section{Musical Preference and Information Dynamics} 853 \section{Musical Preference and Information Dynamics}
811 We are carrying out a study to investigate the relationship between musical preference and the information dynamics models, the experimental interface a simplified version of the screen-based Melody Triangle. 854 We are carrying out a study to investigate the relationship between musical
812 Participants are asked to use this music pattern generator under various experimental conditions in a composition task. 855 preference and the information dynamics models, the experimental interface a
813 The data collected includes usage statistics of the system: where in the triangle they place the tokens, how long they leave them there and the state of the system when users, by pressing a key, indicate that they like what they are hearing. 856 simplified version of the screen-based Melody Triangle. Participants are asked
814 As such the experiments will help us identify any correlation between the information theoretic properties of a stream and its perceived aesthetic worth. 857 to use this music pattern generator under various experimental conditions in a
858 composition task. The data collected includes usage statistics of the system:
859 where in the triangle they place the tokens, how long they leave them there and
860 the state of the system when users, by pressing a key, indicate that they like
861 what they are hearing. As such the experiments will help us identify any
862 correlation between the information theoretic properties of a stream and its
863 perceived aesthetic worth.
815 864
816 865
817 %\emph{comparable system} Gordon Pask's Musicolor (1953) applied a similar notion 866 %\emph{comparable system} Gordon Pask's Musicolor (1953) applied a similar notion
818 %of boredom in its design. The Musicolour would react to audio input through a 867 %of boredom in its design. The Musicolour would react to audio input through a
819 %microphone by flashing coloured lights. Rather than a direct mapping of sound 868 %microphone by flashing coloured lights. Rather than a direct mapping of sound