Hearing Flashcards
What are the two aspects of the ossicles that amplify sound?
- Ratio of the SA of the TM to the footplate of the stapes
- Lever action of the ossicular chain
What are the two aspects of the outer ear that amplify sound?
- Shape of the auricle
- Resonance of the ear canal
Where is high frequency sound heard in the basilar membrane? Low?
High = beginning Low = end
What are the three vestibuli of the cochlea?
Scala tympani
Scala media
Scala vestibuli
What comprises the “cochlear microphone”?
Efferent nerve signals from the organ of corti
Is measuring the cochlear effects on EEG via the auditory brainstem response a measure of hearing?
No–hearing is a subjective perception
What is the gold standard for measuring hearing?
Behavioral testing
What is measured with behavioral hearing testing? (3)
- Hearing level
- Speech reception threshold
- Speech discrimination / word recognition
What is the age at which you can begin auditory testing on a kid? How?
- 6 months
- play therapy and visual reinforcement
What, generally, is an audiogram?
Nomogram of hearing for select frequencies designed to best reflect hearing necessary for language
True or false: a 0 decibel hearing level equates to the lack of acoustic energy
False–0 is the log of 1
What is the scale that is used to measure normative frequencies?
Logarithmic
Any hearing below what log value is normal?
20
What is conductive hearing loss?
Conductive hearing loss occurs when there is a problem conducting sound waves anywhere along the route through the outer ear, tympanic membrane (eardrum), or middle ear (ossicles).
What is sensorineural hearing loss?
a type of hearing loss, or deafness, in which the root cause lies in the inner ear or sensory organ (cochlea and associated structures)or the vestibulocochlear nerve (cranial nerve VIII)or neural part
What is the federal mandate in terms of treating kids with hearing loss?
Must identify and treat by 6 months of age
What is an otoacoustic emission test, in terms of what is being tested?
A test to indicate that cochlear function is intact, but not a hearing test
Is the brain maximally stimulated: noise or quiet?
quiet
What are the limitations of an OAE?
- Very high false positive rate
- Emissions can be absorbed with canal debris (meconium)
How are the limitations of the OAE overcome?
Repeated until positive
What is measured with an auditory brainstem response?
EEG at different sites in the brainstem, with different frequencies
What are the limitations of ABR?
- Requires sedation in children soon after infancy
- Not a measure of hearing
- Only an audiogram can assess the sensory experience of hearing
Is the ABR a measuring of hearing?
No
What is the only test that can be used to measure hearing?
Audiogram
What is tympanometry? What is it used for?
Measure of the compliance of the TM at varying pressure below, at, and above 1 ATM
Determining the status of the middle ear
What is the Type A tympanogram?
Normal–tent graph
What is the Type C tympanogram?
Abnormal with negative air pressure spike on graph
What is the Type B tympanogram?
Abnormal, with no to very little compliance of the TM
What are the two causes of a type B tympanogram?
Perforated large canal volume) or ear drum filled with fluid (small canal volume)
Abnormal amplification of signal = what type of hearing loss?
Conductive
Abnormality of cochlear function of conductive pathways through brainstem = what type of hearing loss
Sensorineural
What is the most common cause of conductive hearing loss in children? Less common?
Middle ear effusion
Less common = auricular atresia
What is the most common etiology of conductive hearing loss in adults? Less common?
-Consequence of long standing chronic ear disease
Less common = otosclerosis
What is the most common cause of sensorineural hearing loss in children? Less common?
Congenital is most common
hereditary is less common, but late onset
What is the most common cause of sensorineural hearing loss in adult? Less common?
Presbycusis
Less common = acoustic neuroma
How can you use percentage points to describe hearing loss?
You don’t
How do you restore mild hearing loss? (3)
- Observation with repeated testing
- Preferential seating
- Hearing amplification
How do you restore moderate hearing loss? (2)
- Surgical
- Hearing amplification
How do you restore severe hearing loss? (3)
- Surgical
- hearing amplification
- Cochlear implant
How do you profound severe hearing loss? (2)
- Cochlear implant
- Alternate means of communication
What is the purpose of the BAHA (using the skull as a tuning fork for the bad ear, to transmit sound to the good ear)?
Allows for 3D representation of sound
What is the major limitation to hearing amplification?
Pain threshold and other auditory phenomena that can decrease speech discrimination with increased amplification
What is stimulated with the BAHA with bilateral conductive hearing loss?
Ipsilateral cochlea
What is stimulated with the BAHA in a unilateral SNHL?
Contralateral cochlea
What is the importance of the ear canal in amplifying hearing
Augments the frequencies that are heard
True or false: the organ of corti is solely an afferent organ
False–there is efferent input as well
What is the idea behind the cochlear microphonic? What is used to measure this?
Mirror image of sounds in the brain
-Auditory brainstem response (ABR)
What does 0 decibels mean in terms of an audiogram?
ratio of sound energy presented to the patient, is the same as the reference sound level for the frequency tested
What is the decibel range that is considered normal hearing?
-10 to 20
What is the decibel range that is considered mild hearing loss?
21-40
What is the decibel range that is considered moderate hearing loss?
41-60
What is the decibel range that is considered moderately severe hearing loss?
61-70
What is the decibel range that is considered severe hearing loss?
70-90
What is the decibel range that is considered profound hearing loss?
90+
