changeset 44:5850b3ebba4b

Final Commit for initial submission to NIME!!

Binary file nime2012/mtriange.pdf has changed

--- a/nime2012/mtriange.tex	Wed Feb 08 03:58:40 2012 +0000
+++ b/nime2012/mtriange.tex	Wed Feb 08 04:44:30 2012 +0000
@@ -58,11 +58,10 @@
 \begin{abstract}
 %The Melody Triangle is a Markov-chain based melody generator where the input - positions within a triangle - directly map to information theoretic measures of its output. 
 
-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 \emph{predictive information rate}\cite{Abdallah:2009p4089} of the random process used to generate the sequnce of notes. These are all related to the \emph{predictability} of the the sequence and as such address the notions of expectation and surprise in
-the perception of music. 
+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 \emph{predictive information rate}\cite{Abdallah:2009p4089} of the random process used to generate the sequence of notes. These are all related to the \emph{predictability} of the the sequence and as such address the notions of expectation and surprise in the perception of music. 
 %Predictive information rate is an information measure developed as part of the Information Dynamics of Music project\footnote{(IDyOM) http://www.idyom.org/}.  It characterises a certain kind of temporal complexity in sequential random processes.
 
-We describe some of the relevant ideas from information dynamics, how the Melody Triangle is defined in terms of these, and describe two physical incarnations of the Melody Triangle. The first is a multi-user installation where collaboration in a performative setting provides a playful yet informative way to explore expectation and surprise in music.  The second is a screen based interface where the Melody Triangle becomes a compositional tool for the generation of musical textures where the user's control is at the abstract level of randomness and predictability. Finally we outline a pilot study where the screen-based interface was used under experimental conditions to determine how the three measures of predictive information rate, entropy and redundancy might relate to musical preference.  	
+We describe some of the relevant ideas from information dynamics, how the Melody Triangle is defined in terms of these, and describe two physical incarnations of the Melody Triangle. The first is a multi-user installation where collaboration in a performative setting provides a playful yet informative way to explore expectation and surprise in music.  The second is a screen based interface where the Melody Triangle becomes a compositional tool for the generation of musical textures; the user's control  at the abstract level of randomness and predictability. Finally we outline a pilot study where the screen-based interface was used under experimental conditions to determine how the three measures of predictive information rate, entropy and redundancy might relate to musical preference.  	
 
 \end{abstract}
 \keywords{Information dynamics, Markov chains, Collaborative performance, Aleatoric composition, Information theory}
@@ -75,7 +74,7 @@
 %as the grammatical analysis of Lerdahl and Jackendoff \cite{Lerdahl:1983} might imply, 
 but as a phenomenon that `unfolds' and is experienced \emph{in time}.   
  
-Information dynamics \cite{Abdallah:2009p4089} considers several different kinds of predictability in musical patterns, how these might be quantified using the tools of information theory, 
+Information dynamics\cite{Abdallah:2009p4089} considers several different kinds of predictability in musical patterns, how these might be quantified using the tools of information theory, 
 %human listeners might perceive these, 
 and how they shape or affect the listening experience.  Central to this is the idea that listeners maintain a dynamically evolving statistical model that enables them to make predictions about how a piece of music will continue.  They do this using both the immediate context of the piece as well as using previous musical experience.  As the music unfolds, listeners continually revise their model; in other words, they revise their own, subjective probabilistic belief state. These changes in probabilistic beliefs can be associated with
 quantities of information; these are the focus of information dynamics.
@@ -136,9 +135,9 @@
 \begin{equation}
 	\mathrm{PIR} = H(\mathrm{Future} | \mathrm{Past}) - H(\mathrm{Future} | \mathrm{Present}, \mathrm{Past}).
 \end{equation}
-It is a measure of the \emph{new} information in each symbol
+It is a measure of the \emph{new} information in each symbol.
 Notice that if the past completely determines both the present and the future (as in the cyclic
-patter above) the PIR is zero, since the present symbol brings no new information. However,
+pattern above) the PIR is zero, since the present symbol brings no new information. However,
 if the symbols in a sequence are generated completely independently, e.g. by rolling a die for each
 one, then again, the present symbol provides no information about the future and the PIR
 is zero. However,  there do exist processes that have high predictive information rates as compared
@@ -233,7 +232,7 @@
 
 The collaborative nature of this installation is an area that merits attention.  By not having one user be able to control the whole narrative, the participants would communicate verbally and direct each other in the goals of learning to use the system and finding interesting musical textures.  This collaboration added an element of playfulness and enjoyment that was clearly apparent. 
 
-As an artefact this installation is an exploratory prototype and occupies an ambiguous role in terms of purpose; it is in a nebulous middle ground between instrument, art installation and technical demonstration.  One thing is clear is that as a vehicle for communicating ideas related to the expectation, pattern and predictability in music to the public, it is very effective.   
+As an artefact this installation is an exploratory prototype and occupies an ambiguous role in terms of purpose; it is in a nebulous middle ground between instrument, art installation and technical demonstration.  It is clear however, that as a vehicle for communicating ideas related to the expectation, pattern and predictability in music to the public, it is very effective.   
 
 \subsection{The Screen Based Interface}
 
@@ -247,29 +246,30 @@
 
 Additionally there are a number of keyboard controls.  These include controls for changing the overall tempo, for enabling and disabling individual voices, changing registers, going to off-beats and changing the speed of individual voices.  The system gives visual feedback to indicate when a token has locked on to a new melody, and contains a buffer zone for allowing tokens to be pushed right to the edges of the triangle without falling out.  
 
-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 a very high and abstract level; predictability, expectation and surprise concepts by which possibilities are explored.
-
+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.
 
 \section{Musical Preference and Information Dynamics Study}
 We carried out a preliminary study that sought to identify any correlation between aesthetic preference and the information theoretical measures of the Melody Triangle.  In this study participants were asked to use the screen based interface but it was simplified so that all they could do was move tokens around.  To help discount visual biases, the axes of the triangle would be randomly rearranged for each participant. 
 
-The study was divided in to two parts, the first investigated musical preference with respect to single melodies at different tempos. In the second part of the study, a background melody is playing and the participants are asked to find a second melody that 'works well' with the background melody. For each participant this was done four times, each with a different background melody from four different areas of the Melody Triangle.  
+The study was divided in to two parts, the first investigated musical preference with respect to single melodies at different tempos. In the second part of the study, a background melody is playing and the participants are asked to find a second melody that 'works well' with the background melody. For each participant this was done four times, each with a different background melody from four different areas of the Melody Triangle.  For all parts of the study the participants were asked to `mark', by pressing the space bar, whenever they liked what they were hearing.   
 
 After the study the participants were surveyed with the Goldsmiths Musical Sophistication Index\cite{Mullensiefen:2011ts} to elicit their prior musical experience. 
  
-\subsection{Results}
-[todo]
+\subsection{Results\label{results}}
+\emph{Note to the reviewers - }
 
+\emph{Due to time constraints we have been unable complete the analysis of the data captured during the study.  The results would be outlined here and will include scatter plots of where in the triangle the subjects `marked' and a heat map indicating where they tended to linger. These will be ready for final version if the paper is accepted.  }
 
-\subsection{Observation/Discussion}
+\subsubsection{Participant Feedback}
 After the experiments the participants were asked to comment on what they thought was happening when they moved the token around the triangle.  They all correctly identified the repetitiveness of the melodies from the low redundancy, low entropy and low information rate area of the triangle, that is the 'repetition' corner (see fig \ref{TheTriangle}).  They all identified the randomness of the high entropy rate corner of the triangle.  Similarly most participants identified the `looping' inherent in the periodic melodies along the `repetition' to `periodicity' edge.
 
-However the descriptions of the intermediate areas and lower edge, that is areas with greater predictive information rate, varied.  Some felt that those areas were quite random and they couldn't really distinguish these from the noise area of the triangle, others found that these were more `interesting' and `melodic' and reported enjoying dwelling there.  Although there seemed to be a positive correlation between these positive ascriptions and the musical sophistication index, our sample size was too small to claim any statistical significance. 
+However the descriptions of the intermediate areas and lower edge, that is areas with greater predictive information rate, varied.  Some felt that those areas were quite random and they couldn't really distinguish these from the `noise' area of the triangle, others found that these were more `interesting' and `melodic' and reported enjoying dwelling there.  Although there seemed to be a positive correlation between these positive ascriptions and the musical sophistication index, the sample size of this pilot study was too small to claim statistical significance. 
+%\subsection{Discussion}
+%\emph{To be completed\dots see \ref{results}}
+\section{Further Work}
+The Melody Triangle has so far only been used with first-order Markov chains for generating content.  This mean that the melodies generated don't have any long term structure or form and hence don't seem to `go anywhere'.  As such the system in its current form is better suited to creating textures and short phrases as oppose to composing over-arching musical structures.  
 
-\section{Further Work}
-In using first-order Markov chains the patterns generated don't have any long term structure or form and as such the melodies generated don't seem to `go anywhere' in the long term.  As it stands the Melody Triangle and is better suited to creating textures and patterns as oppose to composing over-arching musical structures.  
-
-We are currently investigating how higher-order Markov models can be mapped to information theoretic measures and adapting the Melody Triangle to those models.  This would generate a higher level patterns and provide more long-term structures.  
+We are currently investigating how higher-order Markov models can be mapped to information theoretic measures and adapting the Melody Triangle to those models.  This would generate higher level patterns and provide more long-term structures.  Further more sophisticated listener models\cite{Pearce:2005wr}\cite{Potter:2007tt} could be used for computing information measures for more conventional or ecologically valid music.
  
  As it stands, the streams of symbols generated are only mapped to note values.  However they could just as well be applied to any other musical property, such as intervals, chords, dynamics, timbres, structures and key changes.  The possibilities for the Melody Triangle to be compositional guide in these other domains remains to be investigated.