Physiology of Hearing Flashcards
What does frequency dictate?
pitch
What does amplitude dictate?
intensity
What type of sounds are S, D and T?
high frequency
How does the ossicular chain act to transmit sound?
acts as a lever arm with varying efficiency depending on the frequency of sound
What opens the cartilagenous part of the Eustachian tube?
levator palatine
tensor veli palantini
What happens if there is a eustachian tube dysfunction?
negative middle ear pressure
What is the role of the oval and round windows of the cochlea?
allow the transmission of pressure waves in enclosed canals
when the oval window goes in, the round window expands
Where is low frequency heard in the cochlea?
apex
Where is high frequency heard in the cochlea?
base
How are sound waves transmitted to the oval window?
through perilymph fluid
What are the 3 fluid filled compartments of the cochlea?
Scala Tympani
Scala Vestibuli
Scala Media
How many turns are there on the apex of the cochlea?
2.5
Which of the fluid filled compartments are filled with perilymph?
scala vestibuli
scala tympani
Which of the fluid filled compartments are filled with endolymph?
scala media
What fluid filled compartment makes up the vestibular duct?
Scala Vestibuli
What fluid filled compartment makes up the tympanic duct?
Scala Tympani
What fluid filled compartment makes up the cochlear duct?
scala media
How are the perilymph ducts continuous with each other?
Helicotrema
What seperates the Scala media and Scala Tympani?
basilar membrane
What contains the organ or Corti?
basilar membrane
What is the function of the organ of Corti?
connecting mechanica ossilations to electrical impulse transmitted by the vestibuarcochlear nerve
What is the role of the outer hair cells?
to support and modulate
What is the role of the inner hair cells?
recieve sound through the bending of stereocilia when the basilar membrane deplaces downwards, causing K channels to open and therefore depolarise
Where does the action potential hit when it comes along the vestibulocochlear nerve?
E.coli Coclear nuclei superior Olivary complex Lateral lemniscus Inferior coliculus then: primary auditory cortex
At what week should a foetus be able to hear?
18 weeks
At what week will a foetus respond to sound/voice?
26 weeks
How is profound hearing loss usually identified?
newborn screening tests - clicks stimulate hair cells
What are the milestones of hearing?
3 weeks - recognise mothers voice 6 months - babbling, turns to noise 12 months - may make simple noises 12-24months - simple words, syllables 18 months - few words 24 months - 50+ words, understands questions 36 months - sentences
