Auditory System

Front 1

General AP of the Ear Overview: Sound waves go to __ and vibration converts pressure waves into __ energy. This causes the __ to move back and forth. This leads to the conversion into __ waves in the fluid of the cochlea. This stimulates __ in the cochlea. This goes to the __.

Back 1

tympanic membrane; mechanical; ossicles; hydraulic; sensory hair cells; central auditory system

Front 2

Ultimate goal is for sound to reach the __ and the __.

Back 2

inner ear; brain

Front 3

Bypassing the middle ear via air in the middle ear cavity or via bones in the middle ear.

Back 3

bone conduction

Front 4

The __ receives vibrations from the __, transfers them through the tiny __ to the oval window, the port into the inner ear.

Back 4

tympanic membrane; auditory meatus; ossicles

Front 5

Structure in middle ear that contacts airborne sound

Back 5

tympanic membrane

Front 6

Structure in middle ear that has an impedence match between airborne sound.

Back 6

ossicular chain

Front 7

Structure in middle ear that the stapes contacts with the basal end of the cochlea

Back 7

oval window

Front 8

Structure in middle ear that is a pressure release valve for pressure waves in the cochlear fluids

Back 8

round window

Front 9

Structure in middle ear that is a pressure equalization of the middle ear cavity

Back 9

eustachian tube

Front 10

Structure in middle ear that has an acoustic reflex, protects inner ear from acoustic trauma

Back 10

middle ear muscles

Front 11

Two middle ear muscles

Back 11

tensor tympani (CN 5); stapedius (CN 7)

Front 12

Part of cochlea that recognizes low frequencies

Back 12

apex

Front 13

Part of cochlea that recognizes high frequencies

Back 13

base

Front 14

Type of organization of the cochlea

Back 14

tonotopic

Front 15

The basilar membrane starts out __ and gets __.

Back 15

narrow; wider

Front 16

The cochlea's outside structure starts out __ and gets __.

Back 16

wider; narrower

Front 17

The cochlea is tube-like with __ diameter. It has __ turns in humans. It is __ long

Back 17

decreasing; 2.5; 35 mm

Front 18

What section of the cochlea is wider, more flaccid, and has no tension?

Back 18

apex

Front 19

What section of the cochlea is narrower, stiffer, and has some tension?

Back 19

base

Front 20

As the basilar membrane becomes less stiff at the apex, its resonant frequency __.

Back 20

decreases

Front 21

Different frequencies causes __ displacement of the basilar membrane at different locations.

Back 21

maximal

Front 22

The cross-section of the cochlea has three tubes. Name the tubes and their fluids.

Back 22

1) Scala Vestibuli (perilymph)
2) Scala Media (endolymph)
3) Scala Tympani (perilymph)

Front 23

What sensory organ does the scala media contain?

Back 23

organ of corti

Front 24

What structure is atop the hair cells that creates a shearing force?

Back 24

tectorial membrane

Front 25

What has the highest potential in the body?

Back 25

Endocochlear potential

Front 26

Endocochlear potential is only found in the __ of the __.

Back 26

endolymph; auditory system

Front 27

Potential difference across the top of hair cells

Back 27

150 mV

Front 28

Endocochlear potential makes hair cells more effective at __.

Back 28

transducing sound

Front 29

Hair cells are tiny batteries, with an excess of __ charged ions inside and an excess of __ charged ions outside.

Back 29

negatively; positively

Front 30

When there is a difference in charge inside and outside the cell, this is called __.

Back 30

polarized

Front 31

Moving the __ causes tiny pores to open, allowing positive ions to rush into the cell. This is called __.

Back 31

stereocilia; depolorization

Front 32

Less difference between charge on inside and outside of cell

Back 32

Depolarization

Front 33

Reducing the endocochlear potential means depolorization which involves the release of __ to the __ nerve.

Back 33

neurotransmitters; 8th

Front 34

Movement of basilar membrane and outer hair cells involves __.

Back 34

ion channel opening

Front 35

A shearing force causes the influx of __ and __ ions (mechanical gated channels). This leads to __ gated channels. There is then more influx of calcium and potassium into the cell body. Then there is a release of __ to the __.

Back 35

calcium; potassium; electrical/voltage; neurotransmitters; auditory nucleus

Front 36

Cochlea-Cascade of events:
List the 9 steps

Back 36

1) Stapes pushes on oval window
2) Perilymph moves in scala vestibuli
3) Push round window
4) Endolymph moves in scala media
5) Outer hair cells move
6) Basilar membrane moves
7) Ion channels in inner hair cells open
8) Neurotransmitters are released
9)Auditory nerve fibers get stimulated

Front 37

3 Jobs of OHCs

Back 37

1) Amplify response of the IHC (by moving BM)
2) Compression by increasing the range of sounds that are heard
3) Sharpen the response of the IHC

Front 38

The basilar membrane is a "bank" of __

Back 38

band pass filters

Front 39

Each place along the cochlea responds best to a particular __. Each place filters the __ sounds and picks out its favorite signal. This is __ or __. Combining all the best places gives us a bank of many filters: __

Back 39

frequency; complex; tuning; filtering; spectral analysis

Front 40

Cranial Nerve 8: Acoustic Nerve:
List the two classifications, nuclei, and functions

Back 40

Classification: SSA
Nuclei: Vestibular ganglia
Function: Equilibrium and orientation in space

Classification: SSA
Nuclei: Cochlear nucleus
Function: Hearing

Front 41

Injuries to what nerve are associated with disturbances with equilibrium and audition?

Back 41

vestibuloacoustic nerve

Front 42

If a patient has the symptoms of impaired equilibrium, vertigo or dizziness, and nystagmus, what nerve may have a dysfunction?

Back 42

vestibular nerve

Front 43

Two types of hearing impairments

Back 43

conductive; sensorineural

Front 44

Damage to this nerve usually results in a sensorineural hearing loss.

Back 44

auditory nerve

Front 45

What kind of hearing loss is associated with damage to the auditory nerve?

Back 45

sensorineural hearing loss

Front 46

Describe the path of afferent fibers

Back 46

away from cochlea to the brain

Front 47

Describe the path of efferent fibers

Back 47

to the cochlea from the brain

Front 48

Converting sound to neural signals: __ contact hair cells, release __, which causes __ of neuron. If there is enough, there is __. This causes the release of __ in __.

Back 48

dendrites; neurotransmitters; depolorization; an action potential; neurotransmitters; cochlear nucleus

Front 49

Firing rate is described as number of __ per __.

Back 49

spikes per second

Front 50

Most auditory nerve fibers have a max of __ spikes/second

Back 50

500

Front 51

Auditory nerve fibers have spontaneous __. Measure the __ activity.

Back 51

firing; spontaneous

Front 52

Threshold of auditory nerve activity occurs when the __ rate is greater than the __ rate

Back 52

firing; spontaneous

Front 53

What are three important aspects of neural output?

Back 53

1) Frequency tuning
2) Intensity coding
3) Timing

Front 54

List the afferent (ascending) levels of the auditory pathway

Back 54

cochlea, auditory nerve, cochlear nucleus, superior olive, inferior colliculus (midbrain), cortex

Front 55

List the efferent (descending) levels of the auditory pathway

Back 55

cortex, inferior colliculus, superior olive, cochlear nucleus, auditory nerve, cochlea

Front 56

Two functions of efferent fibers

Back 56

1) Protect from damage due to very intense sounds
2) Help to separate signals in noise

Front 57

Where is the first synapse from the cochlea to the brain?

Back 57

cochlear nucleus

Front 58

__ means receiving input from one side.

Back 58

monaural

Front 59

Cochlear Nucleus-1st synapse from cochlea to brainstem:
__: receives input from one side.
Afferents from auditory nerve __ into __ areas.
The first place of parallel processing is in the auditory __. Within each part of the cochlear nucleus is __.
There are inter-connections between parts of the cochlear nucleus. There is a __ code for sounds.

Back 59

monaural; bifurcate; 3; CNS; tonotopy; refining

Front 60

What is the next stage after the cochlear nucleus?

Back 60

superior olivary complex

Front 61

Explain how tonotopy is separated.

Back 61

-Medial superior olive (low frequencies less than 1500 Hz)
-Lateral superior olive (high frequencies greater than 1500 Hz)

Front 62

The medial superior olive has to do with the interaural __ difference between left and right ears.

Back 62

time

Front 63

The lateral superior olive has to do with the interaural __ difference between left and right ears.

Back 63

level

Front 64

Binaural hearing:
What are the two cues for localization?
These cues help with knowing where __ are and separating sounds in a __ environment.

Back 64

1. ITD (time; low frequency)
2. ILD (level; high frequency)
sounds; multitalker

Front 65

With binaural hearing, you also get __. This means that two ears are better than one because the signals add up.

Back 65

binaural summation

Front 66

Explain in terms of the coincidence detection theory what happens when sound comes from the front.

Back 66

The sounds come in at the same time so there is no interaural time difference

Front 67

Explain in terms of the coincidence detection theory what happens when sound comes from the right

Back 67

Sound enters the right ear first so it is localized sooner than the left ear

Front 68

The auditory cortex has all the features of cells in lower areas. This includes (6)

Back 68

frequency, intensity, timing, locations, echoes, speech coding

Front 69

The auditory cortex includes what two processing streams?

Back 69

"what" and "where" (aka ventral and dorsal)

Front 70

In infant hearing screening, intermodulation distortion is measured as an __ in the ear canal. This is used to screen infants for hearing loss.

Back 70

otoacoustic emission

Front 71

Converting sound to neural signals: Redux. List the chain of events, starting with hearing a sound.

Back 71

Hear a sound; up-and-down changes in pressure; up-and-down motion of basilar membrane; neural signals (processed by CNS).