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MRI DAKGAN S I"ULATIO
MOHAN HARIHARA (Tata Consultancy
Services, Bombay)
K.RADHAKRISHNA RAO (IIT, MADRAS)
ABSTRACT
Electronic synthesis of an Indian
percussion instrument is described here.
The system consists of dedicated sound producing circuits controlled by micro computer. Existing composition as well
as self-generated composition can be
played on this system. All the intrica cies of traditional composition,
including variation of tempo are easily
incorporated through software. Potential
applications of this system are in
student training and in the generation of
new compositions.
INTRODUCTION
Electronic music synthesis has been
restricted mostly to stringed and wind
instruments and rarely has simulation of
pertussion instruments been attempted. In
this paper, the simulation of an Indian
percussion instrument, the MRIDANGAM, is
described. Microprocessor based synthe sizers usually burden the processor with
both the tone generation and music compo sition. In contrast, our approach shifts
the burden of tone generation to external
dedicated hardware, leaving the processor
free for the composition alone.
The mridangam is a highly developed
and widely-used percussion instrument in
Indian Classical Music. It is a cylindrical shell made of wood, terminated by multiple, stretched leather membranes on
either side (Fig.l). Sounds are produced
by stroking the membranes with the figures
of both hands,
MSx different sounds, which we will
call strokes, are produced on the right
side (for right-handers) and two on the
left. The strokes on the right side have
higher frequency content than those on the
left, which are generally louder and are
employed for emphasis. Other than these
eight basic strokes there are four sounds
that are combinations of two appropriate
left- and right-side strokes played
simultaneously. Based on Indian classical
rhythmic rules, these twelve strokes are
played in succession to form a composition.
We have restricted our attention to the
solo mridangam composition called
THANIAVARTANAM. Each Thaniavartanam is
bound to a specific THALAM. Thalan is a
periodic sequence, each period consisting
of a fixed number of beats. Based on the
number of beats in a period, thirty five
Thaliams are in vogue. One of the intricate
aspects of a Thaniavartanam is the change
of GATI,or tempo. This is achieved by -
changing the number of strokes played per
beat of the Thalam. There are five Gatis
consisting of three, four, five, seven and
nine strokes per beat or the multiples
thereof. All Thalams and Gatis are easily
generated by appropriate programming of the
microcomputer.
ANALYSIS
Any musical sound is governed by five
parameters (Fig.2)-Attack, Sustain, Harmonic Contents, Decay rate and Release rate.
The parametric dependency of mridangam
strokes is shown in Fig.3.
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ICMC 86 Proceedings
