Acoustics of the Mridangam: Study of a New Design of a South Indian Drum
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Authors
Krishnamurthy, Rohan
Issue Date
2007
Type
Thesis
Language
en_US
Keywords
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Abstract
The mridangam is the primary musical drum of South India and is comprised of three
primary parts: the tonal head, bass head, and central wooden shell to which the two heads are
traditionally fastened by leather thongs. In this study, the acoustical properties of the mridangam
were studied with the traditional mounting system as well as a new mounting system that has
been developed as a convenient and user-friendly method of fastening the heads.
Measurements of modes and mode frequencies were made by mechanically exciting the
heads with a mechanical vibrator and laser vibrometer setup. Drumhead vibration and sound
spectra from standard strokes on both heads were also recorded. Based on the sound spectra and
response curves, the new mounting system seems to maintain the important spectral features of
the traditional design, including the nearly harmonic relationship of the first five modes. This is of practical interest since the new mounting system does not change the basic tonality of the
instrument.
Using a similar analysis, the following conclusions were drawn from measurements of
other practical performance variables: 1) Altering the pitch of the tonal head by an interval of a
fifth with the new mounting system did not change the basic acoustical properties of the
drumhead. 2) Wetting the bass head caused a decrease in bass head frequencies and an overall
damping effect, but did not change the other spectral features of the bass or tonal heads. 3)
Insertion of an iron oxide powder into the tonal head did not detectably change the acoustic
properties of the tonal head. 4) Comparisons of the traditional wheat paste and silicone rubber
on the bass head revealed that the two dampening fixtures generate nearly identical spectra.
Description
24 p.
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