ï~~Proceedings of the International Computer Music Conference 2011, University of Huddersfield, UK, 31 July - 5 August 2011
MODELING SPEED DOUBLING IN CARNATIC MUSIC
Srikumar K. Subramanian, Lonce Wyse, Kevin McGee
National University of Singapore
Department of Communications and New Media
{srikumar.k.subramanian, lonce.wyse, mckevin}@nus.edu.sg
ABSTRACT
We consider the problem of modeling the feature relationships between multiple speed renditions of parts of
compositions called varnams in Carnatic music, discuss
related work in speech and singing synthesis and in synthesizing Carnatic music from solfege notation, present
style dependent but arguably ragd independent rules for
simplifying and adjusting gamakds (continuous pitch movements) in the slower speed performance of one composition to derive the more rhythmic double speed performance and find that the performance derived using these
rules compares favourably with the double speed rendition
by the same artist.
1. BACKGROUND
Salient musical features that depend on speed occur in
some musical genres such as jazz and in Indian classical
music where performers are known to alter musical details of a composition to suit different speeds. In south Indian classical music (called "carnatic music"), the ornate
gamakas (continuous pitch movements) used in a slower
speed are simplified during performance at higher speeds
and have a greater rhythmicity to them than their lower
speed counterparts. The movements in the higher speed
renditions are fewer and appear to follow a rhythmic pulse
determined by the composition's "tala" (time structure).
A transformation involving detail reduction while increasing such rhythmicity appears to be intricate and raises the
question of how much genre knowledge is needed to execute it. The nature of these speed related transformations
is the subject of this paper.
Within carnatic music, compositions in the category
of varnam feature sections that are performed in multiple speeds within a single concert performance. Varnams
therefore are suitable material for studying the changes
that a performer makes to the slower speed rendition when
performing it in a higher speed. A typical varnam consists
of four parts, with the first three making up the first half of
the composition. The first three parts (pallavi, anupallavi
and muktayisvaram) are performed first at a slow speed
and followed by one or more higher speed versions related
to the original speed by simple integer factors. A varnam
performance is guaranteed to at least feature a speed doubled version of the first three parts though a performer
may choose additional speed multiples such as 3/2, 3, 4,
5, 6, 7, 8 and 9. The tald (time structure or meter) is kept
constant throughout the different speeds. The fourth part -
caranam - is by convention performed at double the speed
at which the piece is begun and in this case, the tald is also
doubled in speed. The caranam therefore provides additional raw material to study the characteristics of gamakas
at higher speeds.
Gamakas that feature in the slower speeds cannot be
preserved in the faster speeds. Since the slower speed
already packs much more detail per note, a direct speed
up would require absurd levels of detail in higher speeds
that will be impossible for a performer to execute and will
overload listeners. The work presented here is an attempt
to model the kind of detail reduction that happens when
increasing performance speed.
2. MOTIVATION
Our long term goal is to develop a synthesizer for the
sparse and discrete "prescriptive notation" that is used for
musical communication in the Carnatic genre.' Though
the prescriptive notation omits the all-important gamakas
- complex continuous pitch movements that characterize the genre, trained musicians are able to fill in these
details. Therefore a synthesizer for prescriptive notation
can be said to capture the knowledge that a trained musician brings to the interpretation of a sparsely notated
composition. Understanding the influence of speed on
the choice and structure of gamakas is an important part
of this larger synthesis problem. Performing such detail
reduction of gamakas when given only the slower speed
performance is also an important skill for a student of the
genre. Therefore, computer modeling of this transformation, in addition to contributing to the musicology of the
genre, may have pedagogical applications.
We now discuss work that has been done in the related
areas of jazz swing modeling, text to speech synthesis, expressive music synthesis and gamaka synthesis in carnatic
music.
'The term "prescriptive notation" was introduced by the ethnomusicologist Charles Seeger to denote notation forms that serve as instructions for performers, in contrast with "descriptive notation" which captures the details of a specific performance after the fact [13].
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