Acoustic Immittance Flashcards
Immitance test battery is composed of? (2)
tymapnometry
Acoustic Reflex
potential energy
the energy of position
elasticity
the ability to store potential energy
kinetic energy
the energy of motion
inertia
the ability to store kinetic energy
resistance
the effect of friction, acoustically is called damping
vibration is caused when there is force and is the interplay of (3)
inertia (mass), elasticity (spring/stiffness), and friction (resistance)
stiffness
compliant susceptance (B sub c)
mass
mass suscptance (B sub m)
friction
conductance (G)
acoustic immittance is made of two components
Impedance (Z)
Admittance (Y)
these are the opposite of each other
impedance two portions
resistance (R) and Reactance (x)
reactance breaks down into two parts
mass/inertia (X) and spring/ stiffness/compliance (X)
admittance two portions
susceptance (B) and conductance (G)
susceptance two portions
mass and spring
what happens when you add stiffness to the system?
- has a greater effect at low frequencies
- rising hearing loss (stiffness tilt)
- *this happens with ossicular adhesion, negative ME pressure, etc.
- *to study stiffness characteristics of ME, use a low-probe tone
what happens when you add mass to the system?
- has greater effect o high frequency
- a sloping (falling) hearing loss
- *mass tilt–early in the disease process
- *seen in early stage of OME, ossicular dislocation
- *to study ME diseases that increase system mass, use a high probe tone
increased stiffness______ resonant frequency
increases
increased mass______ resonant frequency
lowers
static acoustic admittance
measure made at extreme positive pressure minus measurement made at maximum compliance
compliance or admittance? tympanometry
admittance because it is both compliance (stiffness) and mass combined which is admittance
Jerger type A
normal peak around 0 daPa *Pressure: +50 to -100mmho or daPa *Compliance: adult: 0.3-1.6cc child: 0.2-0.9cc
Jerger type B
no peak (flat)
- Pressure: flat
- Compliance: no defined peak
- diagnosis is based off of ear canal volume
Jerger type C
negative pressure *Compliance: defined peak at negative pressure adults: >-100 children >-150 *****more negative than these values