Hearing Flashcards
How are wavelength and pitch linked?
As you decrease the wavelength, increase in pitch
What determines the amplitude of the signal? i.e. volume
The displacement of air
What is infrasound?
Anything lower than normal frequency that humans can hear “auditory threshold”
What is ultrasound?
Anything higher than the normal frequency that humans can hear
What is the name for the outer ear?
Pinna
Which bone is the tympanic membrane attached to?
Malleus
Name the 3 ossicles
Malleus
Incus
Stapes
What is a function of the muscles in the middle ear?
Turn down sensitivity to sound when it isn’t required e.g. when eating
Which bone transmits sound waves from the middle ear to the cochlea?
Stapes
What is the name of the structure that the stapes pushes into?
Oval window
What are the main components of the inner ear?
Cochlea
Vestibule
Semi-circular canals
Where is endolymph found?
Scala media
Semicircular canals
Vestibule
Where is perilymph found?
Scala vestibule
Scala tympani
Where is endolymph produced?
Stria vascularis
What creates fluid waves within the cochlea?
Vibration of oval window
How do sound waves escape the cochlea?
Round window
Where are high and low frequencies detected?
High - base of basilar membrane
Low - apex of basilar membrane
What happens when the resonance frequency is activated?
Absorbs all the kinetic energy of the sound wave and effectively stops it at that point
Basilar membrane is pushed up and hair cells are displaced
Why is loss of hearing usually not recoverable?
Support cells do not differentiate well into hair cells
What is the role of outer hair cells?
Alter sensitivity of system which can tune the cochlea by amplifying select frequencies and dampen down areas of pitch of no interest
What happens when you stimulate outer hair cells?
They shorten and stiffen which puts a force through the rods of corti which moves the basilar membrane closer to the tectorial membrane
Which cells are responsible for hearing?
Inner hair cells
What is the function of the rods of Corti?
Maintains relationship between the hair cells and the basilar membrane
Describe signal transduction at the hair cell
Displacement of stereocilia opens potassium channel causing influx and depolarisation
Depolarisation opens calcium channels resulting in influx which causes vesicles to dock onto the synapse and release NT
What happens if hair cells move away from the tallest stereocilia?
Hyperpolarisation –> Inhibition
Where are the dorsal and ventral cochlear nuclei?
Upper medulla
Where do all auditory pathways project?
Medial geniculate nucleus
Which areas of the brain are involved in the arousal responses to noise?
Reticulum
Vermis
How is frequency mapped on the auditory cortex?
High frequencies posterior
Low frequencies anterior
Describe the process of shadow sound
Sound from one side hits the head, which then generates a shadow sounds on the other side of the head, in which the volume is less
Comparison of the signal intensities from both ears determines the ear closest to the sound
Describe the process of sound lag
Sound from a particular direction enters one ear before the other and so there is a slight delay between the sound arriving ipsilaterally at the auditory cortex and that arriving contralaterally
What causes conductive deafness?
Blockage or infection of outer ear
Rupture of tympanic membrane
Ossification of the small ones in the middle ear
What is the cause of sensoneural deafness?
Breakdown of cochlea
Damage to auditory nerve or cortex
What are the names of the 2 tests for deafness?
Rinnes
Webbers
What happens if you lose auditory cortex?
Loss of meaning of sounds as seen in those with Wernickes lesions
