4 - Phys/Pharm Flashcards
give an overview of how hearing works?
- pressure waves travel through the air to ears
- amplified by tympanic membrane
- air vibrations transmit to bony ossicles that relay infor to fluid in inner ear
- fluid wave is created in endolymph at oval window
- transmitted to Organ of Corti
- hair-like structures in endolymph distend = creates an electrical impulse
- conveyed via Vestibular cochlea nerve to cerebral cortex for interpretation as sound
what do the Weber’s and Rinne’s tests test?
for defective conduction of sound through the middle ear or inability of receptors to respond to the sounds reaching them
what is the procedure for the Weber’s test?
- place tuning fork on the midline of skull
- pluck the end
- sound should be heard equally loud in both ear
what is the Weber’s test checking for?
lateralisation of sound
if there is conductive deafness in one ear, what will be the result of the Weber’s test?
sound will be louder in the deaf ear
if there is sensorineural hearing loss in one ear, what will be the result of the Weber’s test?
sound heard louder in good ear
what is the procedure of the Rinne’s test?
- place stem of tuning fork on mastoid process - tests bone conduction
- ask pt to confirm when they can no longer hear the sound
- when pt can no longer hear it, move tuning fork in front of external auditory meatus - tests air conduction
- if they can hear the sound again - suggests air conduction is better than bone conduction = healthy = Rinne’s positive
what is a normal result of the Rinne’s test?
air conduction> bone conduction
positive Rinne’s
what would the Rinne’s test result be for conductive hearing loss?
bone conduction> air conduction
negative rinne’s
what would the Rinne’s test results be for someone with sensorineural hearing loss?
air conduction > bone conduction
positive Rinne’s
what is the typical frequency of tuning forks used in the Weber and Rinne’s test?
512 Hz
when conductive pure tone audiometry, what do the headphone colours mean?
left ear - blue
right ear - red
what is the air-bone gap?
the difference between the audiometry test results of air conduction when compared to bone conduction over the same range of frequencies
what type of ABG do most people have? why is this?
- most ppl have a small ABG
- due to ear being more sensitive to sounds via air conduction compared to bone conduction
if there is no air bone gap - what does this indicate?
an issue in the cochlea/inner ear