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Violin Acoustics

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String completes one oscillation until string is again moving with bow ... Viola: C, G, D, A. Cello, C, G, D, A. Fourths (4/3 ratio) Double Bass: E, A, D, G ... – PowerPoint PPT presentation

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Title: Violin Acoustics


1
Violin Acoustics
  • Physics 332
  • Prof. Hyde-Wright

2
Bowing,Stick-Slip Friction
Bow motion
  • Bow at position L/n suppresses mode n1,2, or,
  • Bow pulls on string until tension is too great.
  • String completes one oscillation until string is
    again moving with bow
  • Bow again pulls on string.
  • Force of bow is automatically synchronized with
    oscillation.
  • Shape of string is travelling triangle wave
  • Dashed line envelope of apex.

3
Vibrations of Sounding Board and Back plate
  • Holograms of vibration patterns at different
    frequencies

4
Violin Architecture
  • (sideways) Vibration of strings transmitted to
    top plate via flexible bridge.
  • Post, directly under side of bridge transmits
    vibrations to backplate.

5
Violin Acoustics
  • Intensity response vs. frequency
  • Bottom curve shows poor violin with tendancy to
    squawk due to excessive response at high
    frequency.

6
Violin/Viol Tuning
  • Fifths (3/2 ratio)
  • Violin G, D, A, E
  • Viola C, G, D, A
  • Cello, C, G, D, A
  • Fourths (4/3 ratio)
  • Double Bass E, A, D, G
  • Viol (Renaissance) D, G, C, E, A, D

7
Harp
  • C-major scale (multiple octaves)
  • Shift all strings of one name up or down one half
    step with pedals

8
Stopped String harmonics
  • Press string lightly a distance L/n from bridge
    to excite nth resonance

Stationary point for 2nd harmonic (n2)
Bow
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