ACOUSTICS OF PERCUSSION INSTRUMENTS

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ACOUSTICS OF PERCUSSION INSTRUMENTS
I. VIBRATIONS OF BARS AND MALLET INSTRUMENTS
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PERCUSSION INSTRUMENTS MAY BE OUR OLDEST MUSICAL
INSTRUMENTS (WITH THE EXCEPTION OF THE HUMAN
VOICE) PERCUSSION INSTRUMENTS INCLUDE
IDIOPHONES (XYLOPHONE, MARIMBA, CHIMES, CYMBALS,
GONGS, ETC.) MEMBRANOPHONES (DRUMS)
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VIBRATIONAL MODES OF A BAR
FREE ENDS
ONE END CLAMPED
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BENDING AND TORSIONAL MODES OF A BAR
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BENDING WAVES IN A BAR
Wave velocity is given by v2 ?K?E/?
?K/cL where K is radius of gyration
Scan Fig. 2.19 in FR
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BARS WITH FIXED AND FREE ENDS
SCAN Fig 2.20 in FR Scan table 2.1 in FR
MODES OF A BAR FREE AT BOTH ENDS
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MODES OF A C6 GLOCKENSPIEL BAR
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MARIMBA
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SOUND OF A MARIMBA
SCAN FIGS 19.4 AND 19.5
IN FR
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TUNING MARIMBA BARS
EFFECT OF REMOVING MATERIAL FROM VARIOUS
LOCATIONS ALONG (a) A UNIFORM RECTANGULAR
BAR (b),(c) A MARIMBA BAR
SCAN FIG 19.6 IN FR
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RESONATORS
SOUND DECAY FOR A MARIMBA BAR WITH (A) AND
WITHOUT (B) RESONATOR
SCAN FIGS 19.8 AND 19.9 IN FR
SOUND LEVELS AT THREE DIFFERRENT POINTS FOR ?/4
(ONE CLOSED END) AND ?/2 (BOTH ENDS OPEN
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BENDING MODES IN A 5-OCTAVE MALLETECH MARIMBA
MARIMBA
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TORSIONAL VIBRATIONS OF A BAR
SCAN EQ 2.72 IN FR SCAN FIG 2.24 IN FR
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TORSIONAL MODES IN A 5-OCTAVE MALLETECH MARIMBA
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MODAL FREQUENCIES OF A XYLOPHONE BAR
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VIBRAPHONE
PHOTO OF A VIBRAPHONE
SCAN FIGS 19.11 AND TABLE 19.3 IN FR
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MALLETS
SCAN FIG 19.12
A MALLET WHOSE MASS NEARLY EQUALS THE DYANMIC
MASS OF THE STRUCK VIBRATOR (ABOUT 30 OF THE
TOTAL MASS FOR A MARIMBA BAR IN ITS FUNDAMENTAL
MODE) TRANSFERS THE MAXIMUM AMOUNT OF ENERGY TO
THE VIBRATOR. ACCORDING TO HERTZS LAW, THE
IMPACT FORCE IS PROPORTIONAL TO THE 3/2 POWER OF
THE MALLET DEFORMATION
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KOREAN PYEONGYEONG
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VIBRATIONAL MODES OFPYEONGYEONG
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FEM CALCULATION SHOWING HOW MODE SHAPE AND
FREQUENCY OF FIRST MODE IN PYEONGYEONG MODEL
DEPEND ON VERTEX ANGLE
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CHIMES OR TUBULAR BELLS
SCAN FIG 19.13 AND TABLE 19.4 IN FR
PHOTOF SET OF CHIMES
O
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WIND CHIMES
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MODE FREQUENCIES FOR A 25-cm TRIANGLE
(OUT-OF-PLANE AND IN-PLANE BENDING MODES
SHOWN)
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TOSCA BELLS
SCAN FIG. 6 IN FLETCHER PAPER
DEVELOPED BY MOYA HENDERSON AND NEVILLE FLETCHER
IN AUSTRALIA
SHAPES OF TWO TOSCA BELLS DERIVED FROM
OPTIMIZATION OF EQUATIONS USING FINE-ELEMENT
PROGRAM TO INCLUDE CORNER BEND RADII (Fletcher,
1993)
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GAMELAN INSTRUMENTS
SCAN TABLE 19.5 AND FIG 19.16 IN FR
JEGOGAN
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TUNING FORK
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CHOIRCHIMES
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CHOIRCHIMES
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TV HOLOGRAPHY SYSTEM
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CHOIRCHIME VIBRATIONS
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