Mercurial > hg > cip2012
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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 |