Evaluation Perceptual Separation in an Pilot System for Affective Composition.

Research evaluating perceptual responses to music has
identified many structural features as correlates that
might be incorporated in computer music systems for
affectively charged algorithmic composition and/or expressive music performance. In order to investigate the
possible integration of isolated musical features to such a
system, a discrete feature known to correlate some with
emotional responses – rhythmic density – was selected
from a literature review and incorporated into a prototype
system. This system produces variation in rhythm density
via a transformative process. A stimulus set created using
this system was then subjected to a perceptual evaluation.
Pairwise comparisons were used to scale differences between 48 stimuli. Listener responses were analysed with
Multidimensional scaling (MDS). The 2-Dimensional
solution was then rotated to place the stimuli with the
largest range of variation across the horizontal plane.
Stimuli with variation in rhythmic density were placed
further from the source material than stimuli that were
generated by random permutation. This, combined with
the striking similarity between the MDS scaling and that
of the 2-dimensional emotional model used by some affective algorithmic composition systems, suggests that
isolated musical feature manipulation can now be used to
parametrically control affectively charged automated
composition in a larger system.