Hearing: cochlea function and types of deafness

Question 1

Is doubling the number of decibels doubling the number of sound energy

Answer 1

No- a 2x increase in sound power is a +3 dB gain in level

Question 2

What does adding 10dB roughly mean

Answer 2

Roughly doubles loudness

Question 3

What does a 3dB reduction in safety levels mean

Answer 3

You double the time you can be exposed for it

Question 4

role of outer ear in hearing

Answer 4

Help determine direction of sound

Question 5

how does sound get transferred from eardrum

Answer 5

ear drum is connected to the malleus which is connected to the incus which is connected to the stirrup

They convert vibration in air to vibration in bone

Question 6

where is the organ of Corti

Answer 6

Sits on top of the basilar membrane

Question 7

What happens after the middle ear vibrates

Answer 7

Cochlea vibrates which moves the basilar membrane up and down

This vibrates stereocilia (hairs) on top of the inner hair cells in the Organ of Corti

Question 8

What happens when the stereocilia vibrate

Answer 8

Tip link on the stereocilia open a channel on the stereocilia and this lets in K+

cell depolarises which lets in Ca2+ and action potential happens.

Question 9

How does action potential travel through brain from ear

Answer 9

Impulse goes up nerve fibres

Go up the auditory nerve

Then the superior part of brainstem-the olivary complex. Auditory nerve joins up with that from other side too

GO up through inferior colliculus

Then to auditory cortex

Question 10

Overview of how we hear

Answer 10

Incoming sound is vibrations in air which are collected by outer ear

• Which are collected by outer ear
• which vibrates ear drum
• Which vibrates the ossicles (malleus, incus, stapes)
• Which vibrates the oval Window on outside cochlea
• Which move fluid inside the cochlear duct
• basilar membrane vibrates
• Vibrates the Organ of Corti so the stereocilia on top of the hair cells go backwards and forwards
• Which pull and push the Tip Links on the stereocilia
• Which pulls open the Transduction Channels on the body of the hair cell
• Which allows Potassium into the Inner Hair Cells
• Hair cells depolarise and fire off action potentials
• goes through the auditory nerve and brainstem to auditory cortex which gives off the perception of a sound

Question 11

What are the flat parts of the ear called

Answer 11

Crura of Antihelix

-Trianglular fossa of anti helix is just where the ear folds inwards

Question 12

Where is Cymba

Answer 12

JUst above the Concha

Question 13

Where is the Intertragic notch

Answer 13

Just above lobes

Question 14

IS there a time delay between which ears get sound

Answer 14

yes if the sound source is on side of one ear if gets sound quicker

Question 15

does HRIR (human related impulse response) differ between person to person?

Answer 15

Yes because shape of everyones ears are different

Question 16

What is lateral third of external auditory meatus like

Answer 16

Cartilagenous

Ceruminous

Sebaceous glands produce earwax

Question 17

What is medial two-thirds of external auditory meatus like

Answer 17

Bony lined with thin skin continuous with the tympanic membrane

Question 18

What is the bit of membrane around the tympanic membrane

Answer 18

Tympanic annulus

Question 19

What are the two parts of the tympanic membrane

Answer 19

Pars flaccida

Pars tensa

Question 20

What are the 3 ossicles in order

Answer 20

Malleus
Incus
Stapes

Question 21

Role of Tensor Tympani in hearing

Answer 21

Inserts into malleus

When tense, reduces the amplitude of vibrations

Question 22

Role of Stapedius

Answer 22

Inserts to stapes

When tense, reduces the amplitude of vibrations

Question 23

what is otitis external

Answer 23

Inflammation of ear Canal (e.g. caused when a foreign body becomes lodged)

Question 24

What is Tympanosclerosis

Answer 24

Scarring of tympanic membrane causing calcium deposits to form

Question 25

What is Otitis Media

Answer 25

Inflammation of the mucus membrane lining the middle ear

Question 26

What is a treatment for otitis media

Answer 26

Inserting a grommet (drainage tube) into tympanic membrane

Question 27

Role of semicircular canals

Answer 27

Allows body to determine motion and balance

Question 28

where do higher frequency sounds vibrate basilar membrane

Answer 28

Closer end

Question 29

where do lower frequency sounds vibrate basilar membrane

Answer 29

further end

Question 30

When is there depolarisation of stereocilia

Answer 30

When they are only moving one way

Question 31

What do the outer hair cells do

Answer 31

Allow inner hair cells to respond to quieter sounds (they amplify)

Sharpen basilar membrane

Question 32

What is otocoustic emissions testing of newborns

Answer 32

Device is put outside baby’s ear. It sends out tiny sounds. IF outer hair cells are working properly, they will amplify that sound. There is also a microphone in device which can pick it up. If baby’s hearing is normal, you can hear sounds back

Question 33

If in an auditory test, the person can’t hear air conduction noises very well but can hear bone-conduction noises, what does this mean

Answer 33

Cochlea is fine

-problem is with the ear bones or ear drum or in ear canal (conductive hearing loss)

Question 34

What is Hearing loss a risk to

Answer 34

Dementia