Physiology and Clinical Aspects of Hearing and Balance Flashcards
What is the ratio of tympanic membrane to stapes footplate?
17:1
How does the middle ear act as a sound amplifier?
The area effect of tympanic membrane ratio to stapes footplate
Lever action of ossicular chain
What is the ratio of pressure of stapes footplate to pressure on malleus?
1.3:1
What is needed in the middle ear for it to work effectively?
Air
What is otitis media with effusion?
Fluid in the middle ear and the tympanic membrane cannot work as effectively, hitting the cochlea
Function of the incus
Transmits vibrations between malleus and stapes
Can the stapes be effected by osteosclerosis?
Yes
Function of the outer hairs of the organ of corti
Fine tuners
Function of the inner hairs of organ of corti
Transmitting messages
How is hearing assessed?
Clinical testing
Tuning fork tests
Audiometry
Objective testing
What are the two tuning fork tests?
Rinne
Webers
What is webers test checking?
A test of lateralisation
What is rinnes test looking at?
Compares loudness of perceived air conduction to bone conduction in one ear at a time
Types of audiometry
Pure tone
Visual reinforcement
Play
Tympanometry
What is pure tone audiometry?
Pure tone air conduction hearing test determines the faintest tones a person can hear at selected frequencies from low to high.
On an audiogram, what would noise induced loss look like?
High frequency hearing loss
Definition of presbyacusis
Hearing loss due to old age
On an audiogram, what would presbyacusis look like?
Low and high frequency hearing loss
High worse
On an audiogram, what would conductive loss show?
Air / bone gap
What can tympanometry detect?
Fluid in the middle ear
Perforation of eardrum
Wax blocking the ear canal
How does tympanometry work?
Pushes air pressure into the ear canal, making the eardrum move back and forth
What does tympanometry measure?
The mobility of the eardrum
What is a graph after tympanometry called?
Tympanograms
Definition of otoacoustic emissions (OAEs)
Sounds given off by inner ear when the cochlea is stimulated by sound
How does OAEs work? Can this be measured?
When sound stimulates cochlea, outer hair cells vibrate
The vibration produces an almost inaudible sound that echoes back to the middle ear.
Yes, can be measured with a small probe in the ear canal
Those with how much hearing loss do NOT produce these very soft emissions?
Hearing loss greater than 25-30 decibels (Dd)
What does the auditory brainstem response (ABR) give information about?
Inner ear (cochlea) and brain pathways for hearing
Another name for ABR
Auditory evoked potential (AEP)
How is the ABR done?
Electrodes on head
Recording brain wave activity in response to sound
Management of hearing loss
Sound amplification
Surgery - outer / middle
Direct stimulus of cochlear nerve cells for profoundly deaf
Who would have a bone anchored hearing aid?
No ear
Susceptible to infection
What makes up the vestibule?
Utricle
Saccule
Semi circular canals
If one canal is stimulated, what happens to the other in the pair?
It becomes inhibited
What has an open connection with the semi circular canals?
Utricle
What are some clinical conditions of the inner ear that affect balance?
Benign paroxysmal positional vertigo
Vestibular neuritis
Meniere’s disease
Definition of tinnitus
Perception of sound within the ear where there is no external stimuli
Explain a negative rhinnes test
Bone conduction > air conduction
