Abnormal Auditory System

Question 1

What are 7 causes of acquired hearing loss?

Answer 1

1.) Noise induced
2.) Aging (Presbycusis)
3.) Ototoxic drugs
4.) Diseases
5.) Trauma
6.) Tumors
7.) Hereditary

Question 2

What is the most common cause of hearing loss?

Answer 2

Noise induced or a lifetime exposure to noise (aging)

Question 3

Where is a conductive hearing loss at?

Answer 3

Outer ear or Middle ear

Question 4

How do you test for a conductive hearing loss?

Answer 4

Air conduction and bone conduction testing

Question 5

How does bone conduction work?

Answer 5

Bone conduction can disturb the fluids in the cochlea by bypassing the middle ear. If patients can hear fine with the bone conduction test, then there is no problem in the cochlea and the problem is likely in the OE or ME

Question 6

What is the Air-Bone Gap?

Answer 6

The difference in how well someone hears sounds through air (headphones) compared to bone vibrations

Question 7

What does conductive hearing loss with the air bone gap tell us?

Answer 7

There is a problem in the ME

Question 8

How do we use AC & BC tests to measure SNHL?

Answer 8

If the AC and BC thresholds look the same, then there is something wrong with the inner ear.

Question 9

What is retrocochlear hearing loss?

Answer 9

Hearing loss beyond the cochlea; a problem with the central auditory pathway

Question 10

What is a mixed hearing loss?

Answer 10

Both conductive and sensorineural hearing loss. The AC and BC tests both come back abnormal

Question 11

How do we know an audiogram shows a noise induced hearing loss?

Answer 11

It is characterized by the 4k notch. There is not much hearing impairment at other frequencies, but a sudden amount in the vicinity of 4000Hz, then it gets better again

Question 12

Why does the 4k notch exist?

Answer 12

HRTF amplifies sounds in some regions more than others. The HRTF provides an extra 20dB of amplification. Because of the structure of the cochlea, you’ll see a hearing loss at 4k because that is the region where sounds are amplified the most by the HRTF.

Question 13

Where in the cochlea are you most likely to see damage in a sensorineural hearing loss?

Answer 13

OHC and stereocilia. They get a bunch of extra movement because of the movement of the tectorial membrane and force exerted on them breaks stereocilia.
If all of the OHC are damaged/gone, then you have 40dB of hearing loss because there is no prestin motility action from the OHC.
IHC and their stereocilia do not get as much action compared to OHC, but can still be damaged with loud noises.

Question 14

How do you measure health of the OHC and stereocilia?

Answer 14

OAEs. If any OAEs are missing, the hair cells have been damaged and if it is sensory damage.

Question 15

What are the 3 types of age related hearing loss?

Answer 15

1.) Sensory
2.) Neural
3.) Strial

Question 16

What is neural hearing loss?

Answer 16

Damage to the synapse of the IHC or beyond. Damage to the release of neurotransmitters or the cells/neurons themselves

Question 17

What is Strial hearing loss?

Answer 17

Damage to the strial vascularis. The SV pushes potassium into the endolymph and retakes the spent K. Damage to the SV can affect the K levels and the lack of them can make the hair cells not fire.