auditory and vestibular systems Flashcards
4 properties of waves
- amplitude (loudness)
- frequency (pitch)
- phase (location)
- waveform (complex qualities)
spectrogram
graph of the power in each frequency band as a function of time
formants
energy in different frequency bands
pinna
reflects sounds to aid in vertical sound source localization
tympanum (ear drum)
vibrates in response to sounds
ossicles (three bonds in middle ear)
conduct vibration from eardrum to cochlea
- amplify vibrations in the fluid filled cochlea
cochlea
organ which converts vibration into electrical signals
cochlear nerve
primary auditory nerve, carries sound info to the brain
semicircular canals
primary sense organs for vestibular sensation
base resonates to
high frequencies
apex resonates to
low frequencies
neural encoding of vibration
inner hair cells are innervated by the dendrites of cells in the spiral ganglion
axons of spiral ganglion cells form the auditory nerve carrying auditory info to the brain
ascending auditory pathway
auditory signals are passed from the cochlea via to auditory nerve to the cochlear nuclei -> superior olivary nuclei and the inferior colliculus (extracts the spatial info of the sound) -> medial geniculate nucleus of the thalamus -> auditory cortex
horizontal localization
done by coincidence detection of signals from the cochlea in the medial superior olive (MSO) - sensitive to differences in timing on the order of microseconds
vertical localization
interpreting the characteristics of sound reflected off of the pinna
primary auditory cortex is located
on the superior bank of the temporal lobe
wernickes area
responsible for understanding the meaning of speech sounds
- patients with damage to this area can neither speak intelligibly nor comprehend spoken language
descending control of cochlea
descending axons from the superior olivary nucleus send axons selectively to outer hair cells. the axons hyperpolarize hair cells via ACh. they have an inhibitory influence on cochlear output
- by reducing the sensitivity to loud sounds, this may increase the dynamic range of cochlea and protect from damage from loud sounds
dynamic range
the range btw the softest and loudest possible sounds which can be represented by a particular neuron
when cells depolarize, hair cells
shorten
when cells hyperpolarize, hair cells
elongate
otoacoustic emission
when active amplification via outer hair cells cause vibration of the cochlear membrane even without external input
hearing loss is caused by
- infection of inner ear
- ototoxic drugs
- ageing
- trauma (loud noises)
tinnitus
ringing sensation that follows trauma or other damage to the auditory system
otolith
utricle and saccule
respond to linear acceleration
semicircular canals
respond to rotational acceleration
vestibular-ocular reflex
stabilizes retinal image by moving eyes to compensate for head movement
