3: Senses - Hearing Flashcards
pinna/pinnae
collect sounds form enviro
ear canal
funneled into by pinnae
tympanic membrane
eardrum
border between outer/middle ear
thin sheet of skin that vibrates in response to sound
concha
works with pinna to filter different frequencies
decibels
difference in amplitude/intensity
frequency
pitch
low = low
high = high
intensity/amplitude
loudness
low = soft
high = loud
pure tone
single frequency, uncommon
complex sound
many frequencies
three smallest bones
ossicles malleus, incus, stapes
oval window
membrane that separates middle/inner ear
middle ear functions
amplifying low intensity sounds
reducing high intensity sounds (acoustic reflex)
cochlea
spiral structure of inner ear
filled with watery fluid in 3 parallel canals (vestibular, middle, tympanic)
organ of corti
structure on the basilar membrane of the cochlea (middle)
composed of specialized neurons (hair cells), dendrites of auditory nerve fibers (terminate at base of hair cells), and cell support
hair cells
four rows, 1 inner/3 outer
inner hair cells
sensory receptors
convert all info about input sound to brain (afferent fibers)
cause release of neurotransmitter/action potentials in neurons of auditory nerve
outer hair cells
motor units
amplify movement of basilar membrane in response to stimulus (efferent fibers)
otoacoustic emissions - sound recorded from external ear canal generated by normal cochlea
high sensitive/sharp tuning, low intensity, frequency resolution
auditory nerve fibers
firing completes process of translating sound waves into patterns of neural activity
traveling waves
.
place code
which fibers are firing
different parts of cochlea to different frequencies
coded by place along cochlear partition with greatest mechanical displacement
temporal code
rate of firing
Helmholtz’s place theory
each basilar membrane location is ind. of other locations (each segment is sensitive to a very limited range of freq)
info about a particular freq is coded by which segment vibrated
peak amplitude
maximum displacement
…
psychoacoustics
study of psych. correlates of physical dimensions of acoustics (branch of psychophysics)
azimuth coordinate
horizontal
right and left
elevation coordinate
vertical
up and down
distance coordinate
how far
interaural time difference
ITD
time diff between the time sound reach the two ears
interaural level difference
ILD
intensity diff of two ears due to sound shadow created by head
head-related transfer function
HRTF
diff between sound from source and the sound actually entering ears
