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RESONANCE

RESONANCE. MUSICAL ACOUSTICS. Science of Sound Chapter 4. Resonance. Resonance occurs when a vibrating system is driven at its natural frequency. The amplitude of the vibrator reaches a maximum, limited only by the damping. PHASE DIFFERENCE BETWEEN CRANK AND MASS.

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RESONANCE

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  1. RESONANCE MUSICAL ACOUSTICS Science of Sound Chapter 4

  2. Resonance Resonance occurs when a vibrating system is driven at its natural frequency. The amplitude of the vibrator reaches a maximum, limited only by the damping.

  3. PHASE DIFFERENCE BETWEEN CRANK AND MASS

  4. STANDING WAVES ON A STRING

  5. OPEN AND CLOSED PIPES OPEN PIPE CLOSED PIPE

  6. STANDING WAVES IN CYLINDRICAL AND CONICAL PIPES

  7. ACOUSTIC IMPEDANCE Acoustic impedance is the ratio of sound pressure p to volume velocity U ZA = p/U

  8. APPARATUS FOR GRAPHING THE ACOUSTIC IMPEDANCE OF WIND INSTRUMENTS GRAPHING ACOUSTIC IMPEDANCE

  9. HELMHOLTZ RESONATOR

  10. HELMHOLTZ RESONATOR

  11. TUNING FORK D.A. Russell, "On the sound field radiated by a tuning fork," Am. J. Phys., 68(12), 1139-45 (2000).

  12. CHOIRCHIMES

  13. CHOIRCHIME VIBRATIONS

  14. SINGING RODS AND WINEGLASSES

  15. SINGING RODS In a bar or rod with free ends the fundamental mode will have a node at its center, and the maximum vibration occurs at the ends (just as in a pipe open at both ends). The next mode has two modes at ¼ L and ¾ L Stroking an aluminum rod with the fingers to excite these longitudinal resonances can create rather loud sounds

  16. SELF-EXCITATION A linear force or motion can excite vibratory motion by a process called self-excitation. Examples of this are the stick-slip motion that excites a wineglass or a violin string

  17. SELF-EXCITATION A linear force or motion can excite vibratory motion by a process called self-excitation. Examples of this are the stick-slip motion that excites a wineglass or a violin string

  18. COLLAPSE OF THE TACOMA NARROWS BRIDGE A DRAMATIC CASE OF SELF-EXCITED OSCILLATION

  19. SYMPATHETIC VIBRATION The vibrating string of a piano or guitar excites the soundboard to vibrate (and thus to produce much more sound). This is called sympathetic vibration. Sympathetic vibration and self-excitation of vibration should not be confused with resonance.

  20. Assignment for January 22 Read Chapter 5 Exercises 1-8 (p.73)

  21. Assignment for January 22 Read Chapter 5 Exercises 1-8 (p.73) For extra credit: Driven harmonic analyzer (“Texas tower”) Make a graphs of amplitude vs frequency and phase angle vs frequency for 2 amounts of damping Show the modes of a wineglass that can be excited by rubbing with a finger; bowing radially with a violin bow; driving it with a loudspeaker. Ref: J. Acoust. Soc. Am. 95, 1108-1111 (1994).

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