Sound Flashcards
3 primary functions of hearing
detecting sound, determining the locations, and recognizing the identity
Sound
results from waves of alternating compressing and rarifying air molecules that are produced by a vibrating source
What is the perceptual dimension associated with amplitude?
loudness
What is the perceptual dimension associated with frequency?
pitch
What is the perceptual dimension associated with complexity?
Timbre
outer ear
funnels sound into ear; emphasizes different aspects of sound spectrum based on location
Middle ear
transfers air sound waves into liquid sound waves
Inner ear
contains receptor cells that transduce sound waves into graded potentials
Outer ear: Pinna
Visible portion, captures sound waves
Outer: Tympanic membrane
thin flap of skin that divides outer and middle ear. Vibrates and moves tiny bones in mid ear and to send into the rest of the ear
Outer: ossicles
tiny bones that vibrate by the eardrum
3 ossicles
malleus (hammer), incus (anvil), and oval window
Malleus (hammer)
connects with eardrum and transmits vibrations via incus
Incus (anvil)
transmits vibrations through the oval window to the cochlea
Oval window
opening in bone surrounding the cochlea
Inner: cochlea
snail-shaped structure filled with fluid. Sound is transferred to liquid medium
Inner: cochlea: organ of corti
hair cells, basilar membrane, tectorial membrane
Organ of coti: hair cells
auditory receptor cells; anchored to basilar membrane ; contain cilia
Organ of coti: basilar membrane
elastic portion running throughout cochlea that splits cochlea into upper and lower part
Path of soundwaves into the brain
1)Sound waves enter outer ear, the ear canal, and the eardrum
2) eardrum vibrates and vibrates bones in the mid ear
3) bones in the mid ear amplify the vibrations and send to the cochlea
4) transduction converses sound waves into electrical impulses
Transduction of hearing
1) vibes cause fluid in cochlea to ripple. Hair cells ride the wave
2) hair cells move causing cilia to bend. Bending causes channels to open which triggers an AP
3) auditory nerve carries electrical signal to the brain, brain recognizes it
Tonotopic representation
different parts of the membrane respond best to different frequencies. High frequencies at base of b.membrane and low frequencies at the apex
place coding
for high to moderate pitches. pitch is determined by firing of hair cells at specific locations of the b.membrane
rate coding
for lower pitches. Pitch is determined by rate of AP’s from hair cells
Perception of timbre is determined by
fundamental frequency, overtones, and perception of spatial location
Perception of pitch is determined by
place and rate coding
Fundamental frequency
corresponds to pitch of a note
Overtones
frequency of complex tones that occur at multiple of the fundamental frequency
Phase differences
the difference in time of an arrival of sound waves in each eardrum.
From ear to brain
1)sound enters from auditory rene and synapses neurons in cochlear nuclei at the level of the brainstem
2)axons cross over to other side of brain, synapsing on the superior olivary nuclei at the level of the brainstem before passing through the lat lemniscus to continue onto the inferior colliculi in the midbrain
3) sound relayed to medial geniculate nucleus of the thalamus and then onto the primary auditory cortex
Perception
dorsal and ventral streams
Dorsal stream
sound localization (where)
Ventral stream
analysis of complex sounds (what)
Auditory agnosia
inability to recognize familiar sounds despite normal hearing of tones
Amusica agnosia
inability to perceive or produce melodic or rhythmic aspects of music
Pure word deafness
cant comprehend spoken word, normal hearing otherwise
Cortical deafness
inability to interpret sound despite normal responses to sudden sound
Vestibular system
balance, maintains head upright, adjustment of eye movement to compensate for head movement
vestibular sacs
respond to force of gravity and inform the brain about the heads orientation
Semi-circular canals
respond to changes in rotation of head
