Hearing Flashcards
What is the sound pressure level measured in?
Decibel scale
What is the pinna and its function
The outer ear, funnels sounds from the environment to the eardrum
What structure exist in the inner ear
Tympanic membrane, ossicles ( malleus incus and stapes)
Tensor tympani muscle
Stapeduis muscle
What is the purpose of the Middle ear
Impedance transformer
Pressure gain from membranes and from lever ratio allows air vibrations to move dense fluid in cochlea
What is the main membrane in the cochlea called and what does it do
Basilar membrane filters sound according to frequency
Where do lower frequency sounds peak along the basilar membrane
Towards to apex ( distal from the entrance)
Where is the organ of clerk situated
On top of the basilar membrane writhing the scale media
What are the different compartments of the cochlea called
Scala vestibuli
Scala media
Scala tympani
How does an inner hair cell work
Forward and backward Displacement of cilia causes a change in membrane potential - transduction links compressed and stretched
What does an outer hair cell do
Motile. Not innervated by fibres. Motion generates vibrations on basilar membrane that are transmitted out of the cochlea as sound. Cochlear amplifier ( except load sounds)
Explain tonotpic organisation of auditory pathway
Neural tuning = tonographic, different brain areas have isomer quench laminae or bands where neurone are tuned similarly - originates in the frequency analysis in the cochlea
What two types of hearing loss are there
Conductive ( external or middle ear conductive before cochlea) compensated by hearing aids,
antibiotics and surgical intervention
Sensorineural- arising in cochle or auditory nerve
What are the types of sensorineural hearing losses
Loss of hair cells or hair cell function- hearing aids little help (trauma drugs infection and congenital)
Auditory nerve (tumour)
Brain stem
Auditory cortex
Non-organic or functional
What is the effect of reduced oxygen on hearing? What are the drugs called that also do this
High threshold broad tuning
Ototoxic
What is invisible hearing loss?
Deafferentation- detachment of nerve fibres from inner hair cells
Occurs with mild noise exposure possibly linear with age
