Anatomy
Point to your tragus.
**
What are the 2 functions of the outer ear?
1. Sound transmission
2. middle ear protection
What are the differences between type 1 and type 2 afferent neurons?
Type 1 = larger in diameter, myelinated, IHC
Type 2 = thinner, not myelinated, OHC
High frequencies vibrate at the _____________.
Base
What is the white reflection on the tympanic membrane?
Cone of light
How does the middle ear combat loud sounds?
Contraction of tensor tympani and stapedius muscle
Where does place coding occur?
Where does temporal coding occur?
basilar membrane
Inner/Outer hair cells
Endolymph is high in ____________.
Potassium
What is full of perilymph? What is perilymph high in?
Scala Vestibuli, Scala Tympani
High: sodium and calcium
Low: potassium
The least helpful to sound transmission:
ossicular level (1.15 times)
Intensity is coded by _______ and ______ of neurons.
number and type
What are 3 differences between inner and outer hair cells?
Afferent vs. efferent neurons
Shape
Number
Function
What sits at the beginning of the scala vestibule?
the oval window
What are 2 theories of hearing?
Place and Temporal
high intensity sounds are coded by...
Low-spontaneous firing rate
Reissner's membrane
What do all of the nerves come together to form?
Spiral Ganglion/Auditory Nerve
Describe the process: outer to inner ear
Pinna - External auditory meatus - TM - Ossicles - Oval Window - Perilymph - Basilar membrane - Hair cell shearing - Opens gate - Potassium enters - Depolarize - Calcium enters - Neurotransmitter - Neuron stimulated
What does the frequency tuning deficit graph show?
Red line = impaired hair cell
Blue line = healthy hair cell
The impaired hair cell does not react to the frequency it is expected to react to.
What are OAE's?
A series of clicks that will measure the outer hair cell's reflection of the stimulus.