1. Antinode
    • point of maximum displacement on a standing wave
    • – Found at the center of the string
  2. First Mode
    • Node at each end and antinode in the center
    • – Longest standing wave pattern
    • – Represents the lowest possible vibration frequency for the string (f0 / 1st Harmonic)
  3. half wavelength resonators
    • tubes with two open ends
    • model for open vocal tract
    • λ = 2L.
    • has a peak amplitude at one end,a zero crossing in the center and a second peak amplitude at the other end.
  4. Quarter Wavelength resonantors
    • tubes open at only one end.
    • has a zero crossing at the closed end and a peak amplitude at the open end.
    • λ=4L
    • Model for ear canal. can only vibrate at odd harmonics
  5. Immitance
    a general term that describes how well energy flows through a system
  6. Impedence (Z)
    • opposition to energy flow.
    • Impedance dictates how much force must be applied to the mass to move it back and forth at a given velocity.
    • the higher the impedance (Z) of the system, the larger the force (F) required to achieve a given velocity (v).
  7. Mass (positive) Reactance (Xm)
    • component of impedance due to mass.
    • • Mass opposes movement due to inertia
    • • Increases with increasing frequency
    • • Opposes high frequency oscillations more than low
  8. Stiffness (negative) Reactance (Xs):
    • component of impedance due to stiffness.
    • Stiffness opposes movement due to restoring force that develops when the spring is displaced.
    • Decreases with increasing frequency • Inversely proportional to the frequency of
    • vibration.
    • Opposes low frequency oscillations more than high.
  9. Resistance (R)
    component of impedance due to friction
  10. Friction
    • opposes movement because the friction between the block and the surface turns some of the energy into heat. • Frequency Independent •
    • Determines how long a system will oscillate •
    • Dissipates energy in the form of heat
  11. Mass & Stiffness Reactance
    • The mass and stiffness components of impedance (Xm and Xs) are 180° out of phase with each other.
    • – And both of them are 90° out of phase with the resistance component of impedance (R)
  12. frequency where the system moves most easily• Frequency with the lowest possible impedance
    • • Frequency at which Xm = Xs, canceling each other out – Therefore, Impedance (Z) = Resistance (R)
    •  At frequencies higher
    • than Rf: Xm > Xs
    •  At frequencies lower than Rf: Xm < Xs
Card Set
flashcard unit 2