Audiology Flashcards
What are the three parts of the cochlea?
Scala vestibuli, scala media, scala tympani
What is contained in the scala vestibuli?
The oval window and Reisner’s membrane. It’s filled with perilymph
What is contained in the scala media?
Reisner’s membrane, organ of corti, stria vascularis. Full of endolymph
What is contained in the scala tympani
the circular window. full of perilymph
What is the oval window?
The oval window is the place where the incus and stapes push against to move the fluid through the cochlea
what is the circular window?
It’s the “exit” of the cochlea. it moves to accomadate pressure
What is Reisner’s membrane?
It’s the thing that separates the scala vestibuli from the scala media
What separates the scala tympani from the scala media?
The baslar membrane
The numatic amplification of the lever action of the malleus, incus, and stapes makes sound how many times louder?
22 times
How many rows of outer hair cells are there?
3
Which two membranes border the organ of corti?
the tectoral membrane (above) and the baslar membrane (below)
what tones are tested in pure tone audiometry?
250, 500, 1000, 2000, 4000, 8000
Threshold is the lowest level the patient responds what percent of the time?
50%
What is the range of normal hearing thresholds for kids?
-10 to 15dB
What is a normal hearing threshold for adults?
25dB
Mild hearing loss is from
26 to 40 dB
difficulty with only faint speech
Moderate hearing loss is from
41 to 55 dB
frequent difficulties with normal speech
Moderate-severe hearing loss is from
56-70 dB
frequent difficulty with loud speech
Severe hearing loss is from
71-90 dB
Can understand only shouted or amplified speech
Profound hearing loss is
91dB+
usually cannot understand even amplified speech
Most speech sounds are between
20-50dB
Air conduction tells us what about hearing loss?
degree
Bone conduction with air conduction tell us what about hearing loss?
type
How do you calculate pure tone average?
add thresholds from 500, 1000, 2000 and divide by three
what is the occlusion effect and what frequencies does it affect?
amplification of low sounds due to covering ears.
250- 30dB
500- 20dB
1000- 10dB
If you have normal air conduction, what will your bone conduction be?
normal
Interaural attenuation is
loss of energy of a sound as it travels from test to non test ear
0 dB bone conduction
40 dB supra aural earphones
50 dB inserts
If you’re using supra aural earphones and send 60dB into your right ear, how much sound would reach the left ear?
20 dB
because interaural attenuation with headphones is 40dB (meaning 40dB are lost to absorption or the environment) 20dB are left to reach the non test ear
If you’re using bone conduction on the mastoid and send 30dB to your left ear, how much sound would reach the right ear?
30dB
because interaural attenuation for bone conduction is zero, meaning no sound is lost so all of it will go the non test ear
Hearing loss is described by
degree shape degree type
ex. mild sloping to severe sensorineural HL
What are the audiogram shapes
flat, rising, sloping, precipitous (more than 20dB difference between 2 octaves)
What is atresia?
Absence of external auditory canal
What is microtia?
abnormally small pinna
What is macrotia?
abnormally large pinna
what is anotia?
absence of pinna
Which syndrome is more predisposed to atresia or stenosis of the EAC?
Treacher collins syndrome
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