Acoustic Drum Exploration

1
Acoustic Drum Exploration

• -A Basis for Investigation-

Ted Argo IV University of Oregon Targo_at_gladstone.u
oregon.edu Working with Prof. Steve
Errede University of Illinois REU 2002
http//www.gmi.edu/drussell/Demos/MembraneCircle/
Circle.html
2
Overview

• Ideal membrane model
• Sound analysis setup
• Effects of deviations from the ideal model
• Conclusions

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Ideal Membrane Model

• Circular Membranes vibrate in certain resonant
  modes.
• Boundary must be fixed.
• Fractionally related.

? Fundamental (0,1) Mode Second (1,1) Mode ?
http//www.gmi.edu/drussell/Demos/MembraneCircle
/Circle.html
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Modes of Vibration
http//hyperphysics.phy-astr.gsu.edu/hbase/music/c
irmem.html
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Sound Analysis Setup
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LabVIEW Setup
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Effect 1 The Drum Shell

• Each shell has specific resonances.
• Shells are made from many different materials.
• Gretsch 13 x 9 Tom
• Resonates at 556 hz, 992 hz, 1549 hz, and 1844
  hz.

www.repercussions.org/ 8gretch_jpg.jpg
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Effect 2 Single Heads

• Distance test
• Center, 1, 2, 3, 4, and 5 inches from center as
  test points.
• Evans Genera G1
• 1 ply drum head.
• Closest to ideal membrane model.
• Evans Genera G2
• 2 plies with a trapped oil layer.
• Large deviation from ideal membrane.

www.drum-set.biz/
9
Effect 3 Sticks

• Different tip shapes and materials may cause
  different harmonics to appear.
• Vic Firth Test Sticks
• 5B Average weight and shape for a band.
• 5BN A 5B with a Nylon Tip.
• Gregg Bissonette Thicker and heavier than a
  5B.

http//www.vicfirth.com/product/manu-facturing/man
ufacturingmain9.html
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Effect 4 Tuning

• Tuning pattern is important to ideal model.
• Different Tensions cause different harmonics.
• Each variable tested at 4-5 different tensions.

Drum Head Tuning Pattern
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Effect 5 Resonant Head

• By adding a second head,many new resonances
  appear.
• Both heads have individual resonances.
• There are beats between the two heads creating
  more internal frequencies.

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Effect 6 Distance

• The distance from the center at which the head is
  struck determines its sound.

• Distance tests at 6 distances
• Every inch from center.
• Each other test at 3 distances
• Center, 2 inches, and 4 inches.

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Other Considerations

• Hardware on the shell
• Interrupts sound path.
• Damps shell resonances.
• Bearing edge
• Variously pointed or rounded edges.
• Changes coupling of head to shell.
• May change boundary conditions of ideal membrane.

Bearing edges and hardware
www.acousticdrums.com/ members/refinish.html
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Conclusions

• The ideal membrane model does not hold for a
  complex drum system.
• There are many different deviations from the
  ideal model.
• Some real-world playing preferences are
  observable.
• More tests can be performed on different
  equipment.
• This is the low-cost easy-accessibility solution.

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Acknowledgments

• Prof. Steve Errede Project Advisor.
• Nicole Drummer Equipment and ideas.
• Adam Kempton and Eric Moon Sharing Lab Space.
• University of Illinois Hosting the REU
  program.
• The National Science FoundationThis material is
  based upon work supported in part by the National
  Science Foundation under Grant No. 9987906. Any
  opinions, findings, and conclusions or
  recommendations expressed in this material are
  those of the author and do not necessarily
  reflect the views of the National Science
  Foundation.