Index of /~echew/presentations/MaMuX2004

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[   ] ec-MaMuX-20040521.pdf   11-Oct-2004 20:07  2.9M  
[   ] ec-MaMuX-20040522.pdf   11-Oct-2004 20:10  2.2M  

In this directory are the PDF files for the 
MaMuX seminars on May 21-22, 2004,
organized by Moreno Andreatta, on 

"Computational tools for musical analysis.
Logics and transformational theories in music."
("Outils informatiques en analyse musicale.
Logique et theories transformationnelles en musique."):

[1] "Messiaen's Regard IV: Automatic segmentation using the Spiral Array"
    21 May 2004, 1100h - 1145h

[2] "Pitch Spelling: A Computational Approach Using the Spiral Array"
    22 May 2004, 1100h - 1145h

by Elaine Chew (echew@usc.edu)

Seminaire MaMuX
Mathmatiques, musique et relations avec d'autres disciplines
IRCAM, salle Igor Stravinsky
1, place Igor-Stravinsky 75004 Paris
May 21-22, 2004.

The MaMuX website is at 
http://recherche.ircam.fr/equipes/repmus/mamux/

Click on ec-MaMuX-20040521.pdf for presentation [1].
Click on ec-MaMuX-20040522.pdf for presentation [2].

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"Messiaen's Regard IV: Automatic segmentation using the Spiral Array"
Elaine Chew (echew@usc.edu)

ABSTRACT: The presentation of Friday 21th will introduce a
computationally efficient method for automatic segmentation and report
its results when applied to Messiaen's Fourth Regard. The O(n)
algorithm uses the Spiral Array model to segment music according to
pitch patterns. The Spiral Array represents pitches in three
dimensional space and summarizes pitch collections using spatial
points, called centers of effect (c.e.'s) in the structure's
interior. The c.e. serves a s a proxy for the pitch context. At each
point in time, the distance between the past and future
c.e. quantifies the discrepancy between the respective contexts. This
distance peaks at each segmentation boundary. The method is applied to
the fourth piece in Messiaen's Vingt Regards. An interesting question
that arises is: Can a method typical used for tonal analysis be
applied to Messiaen's music?

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"Pitch Spelling: A Computational Approach Using the Spiral Array"
Elaine Chew (echew@usc.edu)

ABSTRACT: The talk of Saturday 22th presents algorithms for pitch
spelling using the Spiral Array model. Accurate pitch spelling,
assigning contextually consistent letter names to pitch numbers (for
example, as in MIDI), is a critical component of music transcription
and analysis systems. The algorithms seek to assign the optimal
spellings using the Spiral Array model, a geometric model embodying
the relations in tonality. They do not require the key context to be
determined; instead, they use the center of effect (c.e.), an interior
point in the Spiral Array model, as a proxy for the key
context. Plausible pitch spellings are measured against this c.e., and
the optimal pitch is selected using the nearest neighbor
criteria. Various strategies for determining this contextual c.e. are
explored. The local context is found to be more important than the
global, but a combination of both achieves the best results. This is
work done in collaboration with Yun-Ching Chen.