hearing Flashcards
what is sound
pressure wave caused by oscillating molecules
what does frequency dictate
pitch amplitude and intesnity
process of hearing step one
external ear collects sound and directs sound waves into the tympanic membrane
process of hearing step 2
vibrations arrive at the tympanic membrane triggering vibrations there
what does the vibration stimulate
ossicular chain of middle ear which transmits the energy to the cochlea
what does the middle ear act as
an amplifier mechanism
other name for tympanic membrane
eardrum
role of tympanic membrane
seperates outer ear from middle ear
what happens when vsound waves reach the tympanic membrane
cause it to vibrate
vibrations are then transferred to the tiny bones in middle ear
action of inner earv
recieves mechanical signals from middle ear and converts them into electrical signals
what does the vibration create
pressure waves in perilymph of cochlea
what happens as a result of wave motion transmission to endolymph
basilar membrane vibrates causing the hair cells at the organ of corti to move against the tectoral membrane stimulating depolarisation
what does depolariston result in
stimulation of cn viii and then the central pathways
where do electrical signals culminate
brodman areas 41/42 of the primary auditory cortex within the superior temporal gyrus
what happens to the pressure waves in the cochlear
descend and become vibrations again and are dampened at the round window
when can foetus hear
18 weeks
when do foetus respond to sound/ voice
26 weeks
what is fundamnetal for normal speech development
normal or good hearing
normal development of baby
3 months- cooing, recognises mothers voice
6 mmonths- babbling, turns to sound and eyes toward sound, happy and sad sounds
12 months- simple noises
18 months- few words
24- two word phrases - understands commands
24-36 - 3 word sentences
inner hiar cells action
involved in receiving sound and passing it up auditory nerve
outer hair cells action
involved in modulating sound
summary of ear part roles
External ear - sound collector
Middle ear - mechanical force amplifier
Inner ear - sound transducer / analyser
