Mercurial > hg > cip2012

Binary file draft.pdf has changed
--- a/draft.tex	Sat Mar 17 01:03:15 2012 +0000
+++ b/draft.tex	Sat Mar 17 02:00:10 2012 +0000
@@ -638,8 +638,7 @@
 	$(x_{t+1},\ldots,x_{t+N})$ from the base model. The next
 	observation $\hat{x}_{t+1}$ encodes the block of $N$ obtained by shifting the previous
 	block along by one step. The new Markov of chain is parameterised by a sparse $K^N\times K^N$
-	transition matrix $\hat{a}$. Adopting the label $\mu$ for the order $N$ system,
-	we obtain:
+	transition matrix $\hat{a}$, in terms of which the PIR is
 	\begin{equation}
 		h_\mu = h(\hat{a}), \qquad b_\mu = h({\hat{a}^{N+1}}) - N h({\hat{a}}),
 	\end{equation}
@@ -803,7 +802,7 @@
 represented by a click track, and the algorithm takes as input event
 times for discrete kick and snare drum events relative to this click
 track. These are obtained using dedicated microphones for each drum and
-using a percussive onset detector (Puckette 1998). The drum tracker
+using a percussive onset detector \cite{puckette98}. The drum tracker
 continually updates distributions for tempo and phase on receiving a new
 event time. We can thus quantify the information contributed of an event
 by measuring the difference between the system's prior distribution and
@@ -914,7 +913,7 @@


  \begin{fig}{mtriscat}
-	\colfig{mtriscat}
+	\colfig[0.9]{mtriscat}
 	\caption{The population of transition matrices distributed along three axes of
 	redundancy, entropy rate and predictive information rate (all measured in bits).
 	The concentrations of points along the redundancy axis correspond
@@ -955,7 +954,7 @@
 % Or, conversely, are predictable, but not entirely so.

 \begin{fig}{TheTriangle}
-	\colfig[0.9]{TheTriangle.pdf}
+	\colfig[0.8]{TheTriangle.pdf}
 	\caption{The Melody Triangle}
 \end{fig}

@@ -994,8 +993,6 @@


-\subsection{Information Dynamics as Evaluative Feedback Mechanism}
-%NOT SURE THIS SHOULD BE HERE AT ALL..?

 \begin{fig}{mtri-results}
 	\def\scat#1{\colfig[0.42]{mtri/#1}}
@@ -1003,8 +1000,8 @@
 	\begin{tabular}{cc}
 %		\subj{a} \\
 		\subj{b} \\
-		\subj{c}
-%		\subj{d}
+		\subj{c} \\
+		\subj{d}
 	\end{tabular}
 	\caption{Dwell times and mark positions from user trials with the
 	on-screen Melody Triangle interface, for two subjects. The left-hand column shows
@@ -1015,6 +1012,9 @@
 	that point before the point was marked.}
 \end{fig}

+\comment{
+\subsection{Information Dynamics as Evaluative Feedback Mechanism}
+%NOT SURE THIS SHOULD BE HERE AT ALL..?
 Information measures on a stream of symbols can form a feedback mechanism; a
 rudimentary `critic' of sorts.  For instance symbol by symbol measure of predictive
 information rate, entropy rate and redundancy could tell us if a stream of symbols
@@ -1025,35 +1025,55 @@
 the short term properties of a work.  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.
+}

-\section{Musical Preference and Information Dynamics}
-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.  Participants are asked
-to use this music pattern generator under various experimental conditions in a
-composition task.  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.  As such the experiments will help us identify any
-correlation between the information theoretic properties of a stream and its
-perceived aesthetic worth.
+\subsection{User trials with the Melody Triangle}
+We are currently in the process of using the screen-based
+Melody Triangle user interface to investigate the relationship between the information-dynamic
+characteristics of sonified Markov chains and subjective musical preference.
+We carried out a pilot study with six participants, who were asked
+to use a simplified form of the user interface (a single controllable token,
+and no rhythmic, registral or timbral controls) under two conditions:
+one where a single sequence was sonified under user control, and another
+where an addition sequence was sonified in a different register, as if generated
+by a fixed invisible in one of four regions of the triangle. In addition, subjects
+were asked to press a key if they `liked' what they were hearing.

-Some initial results for four subjects are shown in \figrf{mtri-results}. Though
-subjects seem to exhibit distinct kinds of exploratory behaviour, we have
-not been able to show any systematic across-subjects preference for any particular
-region of the triangle.
+We recorded subjects' behaviour as well as points which they marked
+with a key press.
+Some results for three of the subjects are shown in \figrf{mtri-results}. Though
+we have not been able to detect any systematic across-subjects preference for any particular
+region of the triangle, subjects do seem to exhibit distinct kinds of exploratory behaviour.
+Our initial hypothesis, that subjects would linger longer in regions of the triangle
+that produced aesthetically preferable sequences, and that this tend to be towards the
+centre line of the triangle for all subjects, was not confirmed. However, it is possible
+that the design of the experiment encouraged an initial exploration of the space (sometimes
+very systematic, as for subject c) aimed at \emph{understanding} the parameter space and
+how the system works, rather than finding musical sequences. It is also possible that the
+system encourages users to create musically interesting output by \emph{moving the token},
+rather than finding a particular spot in the triangle which produces a musically interesting
+pattern by itself.

-Subjects' comments: several noticed the main organisation of the triangle:
-repetative notes at the top, cyclic patters along the right edge, and unpredictable
-notes towards the bottom left (a,c,f). Some did systematic exploration.
-Felt that the right side was more `controllable' than the left (a,f)---a direct consequence
+Comments collected from the subjects during and after the experiment suggest that
+the information-dynamic characteristics of the patterns were readily apparent
+to most: several noticed the main organisation of the triangle,
+with repetative notes at the top, cyclic patterns along one edge, and unpredictable
+notes towards the opposite corner. Some described their systematic exploration of the space.
+Two felt that the right side was more `controllable' than the left (a direct consequence
 of their ability to return to a particular periodic pattern and recognise at
-as one heard previously. Some (a,e) felt the trial was too long and became
-bored towards the end.
-One subject (f) felt there wasn't enough time to get to hear out the patterns properly.
-One subject (b) didn't enjoy the lower region whereas another (d) said the lower
+as one heard previously). Two said that the trial was too long and became bored towards the end,
+but another felt there wasn't enough time to get to hear out the patterns properly.
+One subject did not `enjoy' the patterns in the lower region, but another said the lower
 regions were more `melodic' and `interesting'.

+We plan to continue the trials with a slightly less restricted user interface in order
+make the experience more enjoyable and thereby give subjects longer to use the interface;
+this may allow them to get beyond the initial exploratory phase and give a clearer
+picture of their aesthetic preferences. In addition, we plan to conduct a
+study under more restrictive conditions, where subjects will have no control over the patterns
+other than to signal (a) which of two alternatives they prefer in an A/B forced
+choice paradigm, and (b) when they are bored of listening to a given sequence.
+
 %\emph{comparable system}  Gordon Pask's Musicolor (1953) applied a similar notion
 %of boredom in its design.  The Musicolour would react to audio input through a
 %microphone by flashing coloured lights.  Rather than a direct mapping of sound
@@ -1077,7 +1097,6 @@
 information rate' that characterises the surprisingness and predictability of
 musical patterns.

-
 We have outlined how information dynamics can serve in three different forms of
 analysis; musicological analysis, sound categorisation and beat tracking.