Transcript Acoustic Drum Exploration -A Basis for InvestigationTed Argo IV University of Oregon [email protected] Working with Prof.

Acoustic Drum Exploration
-A Basis for InvestigationTed Argo IV
University of Oregon
[email protected]
Working with Prof. Steve Errede
http://www.gmi.edu/~drussell/Demos/
MembraneCircle/Circle.html
University of Illinois REU 2002
Overview
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•
•
•
Ideal membrane model
Sound analysis setup
Effects of deviations from the ideal model
Conclusions
Ideal Membrane Model
• Circular Membranes
 Fundamental (0,1) Mode
Second (1,1) Mode 
http://www.gmi.edu/~drussell/Demos/
MembraneCircle/Circle.html
vibrate in certain
resonant modes.
• Boundary must be
fixed.
• Fractionally related.
Modes of Vibration
http://hyperphysics.phy-astr.gsu.edu/hbase/music/cirmem.html
Sound Analysis Setup
Computer
LabPC Card
Microphone
Drum
LabVIEW Setup
Sampling
Parameters
Data Saving
Entries
Oscilloscope
Trace
FFT Graph
Peak Detection
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
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/
Effect 3: Sticks
• Different tip shapes
and materials may
cause different
harmonics to appear.
• Vic Firth Test Sticks:
• 5B – Average weight
http://www.vicfirth.com/product/manufacturing/manufacturingmain9.html#
and shape for a band.
• 5BN – A 5B with a
Nylon Tip.
• Gregg Bissonette –
Thicker and heavier
than a 5B.
Effect 4: Tuning
• Tuning pattern is
Drum Head Tuning Pattern
important to ideal
model.
• Different Tensions
cause different
harmonics.
• Each variable tested at
4-5 different tensions.
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.
Tuning Summary: Genera G2 Batter, G1 resonant, Vic Firth 5BN Sticks, Gretsch 13"X9" Tom
1.78
1.81
2.69
3.14
3.86
5.13 Mode Multiple
148.14
262.79
268.26
398.31
464.63
570.58
758.85 Average Frequencies
0.03
0.01
0.02
0.01
0.01
0.01
0.01 Average Amplitudes
0.00
0.00
0.00
0.00
0.00
0.00
0.00 Average Error
1.81
2.10
1.51
12.65
11.76
0.00
2.57 Percent Error
1.00
0.33
0.72
0.20
0.25
0.15
0.24 Normalized Amplitude
0.02
0.01
0.01
0.03
0.03
0.00
0.01 Normalized Error
Down a quarter turn
Effect 6: Distance
•Distance tests at 6 distances:
•Every inch from center.
•Each other test at 3 distances:
•Center, 2 inches, and 4 inches.
• The distance from the
center at which the head is
struck determines its sound.
Other Considerations
• Hardware on the shell
• Interrupts sound path.
• Damps shell resonances.
• Bearing edge
Bearing edges and hardware
• Variously pointed or
rounded edges.
• Changes coupling of
head to shell.
• May change boundary
conditions of ideal
membrane.
www.acousticdrums.com/ members/refinish.html
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.
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 Foundation:
This 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.