Hearing Loss Flashcards
T/F: The external ear has a passive role in the hearing process
T
T/F: The malleus, incus, and stapes act as acoustic resonators
F
The concha and EAC act as acoustic resonators to amplify sound at frequency levels of 2000 Hz to 4000 Hz (for EAC)
What are the differences among peripheral auditory system, central vestibular system, and central auditory system?
Peripheral auditory: divided into 3 parts: external, middle, and inner ear that receives and processes air-pressure variations into neural signals
Central Auditory System- responsible for interpreting or recognizing the acoustic information brought by the neural signals
Central vestibular system- for balance and stability (spatial orientation)
What is the main function of the middle ear?
Impedance Matching
Explain impedance matching
Impedance matching matches the low impedance airborne sounds from the EAC with the high impedance fluid of the inner ear (it equalizes it)
the middle ear boosts the pressure at the tympanic membrane by 200x as it reaches the inner ear through the ossicles, alllowing transmission of sound despite the air-fluid boundary
What are the three ossicles?
Malleus, Incus, Stapes
Impedance matching is composed of these 3 parts:
- Area effect of the tympanic membrane: its area of 55mm^2 being bigger than the stapes footplate having 3.2mm^2 creates a 17:1 increase in sound energy
- The size differences and lever action of the ossicles: Malleus being 1.3x longer than the incus gives off a 25db increase in sound (22:1 transformer ratio)
- The oval window near the stapes being bigger than the round window in the inner ear also results in a 4db increase in sound frequency
Explain the hearing process in the external ear
The pinna (auricle) funnels sound waves into the EAC, which transmits the sound into the tympanic membrane, resulting to its vibration.
explain the hearing process in the inner ear
The impedance matching in the middle ear results in amplified sound -> vibrates the fluid (endolymph and perilymph) and transmitted as pressure waves in the scala vestibuli -> moving to the roof of the scala media (Reissner’s membrane) -> down to the basilar membrane where hair cells are present (floor of scala media) -> pressure waves disspates in the round window
T/F: Less displacement cause less sensory receptors and neurons being stimulated, leading to decreased sound intensity
T
T/F: Maximum deflection occurs at different sides along the membrane
T
Highest sound frequency is found at?
The base
Lowest sound at the apex
Nerve that connects the basilar membrane to the central auditory system
Vestibulocochlear nerve
T/F: Each area of the cortex represents a different part of the basilar membrane -> different pitch
T
What is the central auditory system pathway?
COLIMA
Cochlear nucleus -> Superior Olivary Complex -> Lateral Lemniscus -> Inferior Colliculi -> Medial Geniculate Body -> Auditory Cortex
T/F Nerve is not involved in retrocochlear hearing loss
F
Nerve is involved
T/F Hearing loss can both be conductive and sensorineural
T
it can occur otgether
Interpretation of this WEBER TEST:
Sound is heard midway and equal on BOTH ears
NORMAL
Interpretation of this WEBER TEST:
Lateralizes to affected ear
Patient hears better in the affected ear because ambient noise is reduced
What is the result on weber if interpretation is sensorineural?
Patient hears better on the better/normal ear
INTERPRET THIS RINNE TEST:
Sound is louder when lateral to EAC
RINNE POSITIVE, where air conduction is louder than bone conduction
Interpretation: Normal or sensorineural
INTERPRET THIS RINNE TEST
Sound is louder when touching the mastoid
(-) Rinne
Bone conduction is louder than air conduction
INTERPRETATION: Conductive
T/F: Rinne test is performed on the lateralized side on Weber test
T
but rinne test is also done (but in both sides) if weber test is midline
Requires an active and
voluntary response
a. Behavioral Audiometry
b. Objective Audiometry
a. Behavioral Audiometry
Tests the involuntary
physiologic response
a. Behavioral Audiometry
b. Objective Audiometry
b. Objective Audiometry
Type of behavioral audiometry test for <6 mos
Behavioral Observation Audiometry
- eyes or startle reflex are checked
Type of behavioral audiometry test for 6-24 months
Visual Reinforcement Audiometry
Head turning is checked
Type of behavioral audiometry test for 2-4 yo
Play audiometry
set tasks
3 main types of response in objective audiometry
- Immittance measurement
- Otoacoustic emissions
- Auditory evoked potentials
T/F: Otoacoustic emissions of objective audiometry measure changes in acoustic impedance
F - immitance measurement
Has 2 main types: Stapedial reflex and Tympanometry
T/F:↓ impedance = ↓ reflection, ↑ absorption/compliance
T
What is the stapedial reflex?
It is when the stapedius muscles on both sides contract via the acousticofacial reflex arc despite sound being delivered only on one ear
This threshold is the minimum sound pressure
level needed to produce a measurable change in tympanic
membrane impedance.
Stapedial Reflex
Measure the tympanic membrane mobility or compliance
which is the stapedial response
Stapedial Reflex
Tests middle ear function by transmission of sound energy
Evaluates eardrum compliance and eustachian tube function
Tympanometry
T/F Tympanometry can evaluate eardrum compliance and detect fluids in the middle ear and perforations
T
T/F Tympanometry evaluates hearing loss and can identify contributing factors
F
It does not evaluate hearing loss, but it can identify factors
This objective audiometry is used to screen cochlear functions in newborns
Otoacoustic Emissions
This Reflects functional integrity of the outer hair cells in the
inner ear
Otoacoustic Emissions
This objective audiometry differentiates between cochlear and retrocochlear hearing loss
Auditory brainstem response
T/F OAE is done as a confirmatory test after a questionable auditory brain response
F
Auditory brain response is done as confirmatory test after a questionable OAE
T/F Auditory BRainstem response measures bioelectrical potentials from the cochlea, auditory nerve, and the CNS
T
T/F Sensorineural hearing loss is associated with inner ear damage and possibly the cochlear nerve
T
T/F Conductive hearing loss can be brought to a baby by a pregnant mother exposed to rubella
F : Sensorineural hearing loss
Other infections could be toxoplasmosis, congenital syphilis, CMV, HSV, meningitis, labyrinthis, otitis media, mumps
Drugs: Quinine, Alcohol, Thalidomide
Noise level limit
85db
How does medications cause ototoxicity?
Ototoxic medications can cause death of sensory hair cells
Symmetric effects
T/F Cisplatin (chemotherapeutic agent) can cause ototoxicity
T: also furosemide, aminoglycosides, quinine, salicylates (Aspirin)
T/F Tumors of internal auditory canal can cause retrocochlear hearing loss
T
T/F Sensorineural loss is a problem in the central auditory system
T
Which is incorrect?
a. Normal hearing ability - <25Hz
b. Moderate hearing loss - 55 Hz
c. Severe hearing loss - 75 Hz
d. Profound hearing loss - 85 Hz
D. Profound Hearing Loss
Normal hearing ability - <25Hz
Moderate hearing loss - 40-60 Hz
Severe hearing loss - 70-90 Hz
Profound hearing loss - 90-120 Hz
Which hearing loss typically presents as muffled sensation and ringing in the ear?
Noise-induced hearing loss
What tympanometry result will show if px has middle ear effusion?
Type B: Flat/very low, rounded peak
What tympanometry result will show if px has impaired middle ear ventilation?
Type c: Peak is shifted to a negative pressure
What tympanometry result will show if px has tympanosclerosis?
Type As: Shallow peak
Tympanic membrane has reduced compliance
3 main types of objective audiometry
-Imittance Measurement (Stapedial Reflex, Tympanometry)
-Otoacoustic Emissions (screens cochlear fxns in newborns)
-Auditory Evoked Potentials (measures potentials from the cochlea, auditory nerve, CNS)
Types of Sensorineural-cochlear hearing loss
Noise-Induced Hearing Loss
Ototoxicity
Presbicusis
