Hearing pt 1 (II) Flashcards
amplitude
perceives as loudness
dB (decibels)
frequency
- number of cycles per second of vibration
- hertz
- perceived as pitch
range of human hearing **depending on age
20 Hz - 20,000 Hz
external ear
- funnels sound
- pinna
- ear canal
pinna
- part of external ear
- collect sound waves
- works as funnel
- pushes waves into ear canal
ear canal
- part of external ear
- auditory canal
middle ear
- concentrates sound energy
- 3 ossicles
- tensor tympani
- stapedius
- eustachian tube
3 ossicles
malleus
incus, stapes
tensor tympani
- part of middle ear
- attached to the malleus and tympanic membrane
stapedius
- part of middle ear
- attached to the stapes
acoustic reflex
- when activated, the muscles stiffen ands reduce sound’s effects.
eustachian tube
- part of middle ear
- equalizes pressure on both sides
- ears pop
- opens when you swallow and with positive pressure
cochlea
- has 3 parallel canals
- filled with endolymph
scala vestibuli
- vestibular canal
- inner ear
- cochlea
scala media
- middle canal
- contains organ of corti
- inner ear
inner ear
- transduces sound into neural activity
- 3 canals in the cochlea
organ of corti
receptor system that converts vibration into neural activity
scala tympani
- inner ear
- in cochlea
- tympanic canal
hair cells
- don’t fire action potentials
- they do depolarize resulting in a receptor potential
cilia tips of hair cells are joined by….
a tip links
inner hair cells
- carry out signal transduction
- release glutamate
- respond to specific sound frequencies
outer hair cells
- amplify and refine cochlea to help discriminate frequencies
the 3 “changes” in OHCs
- hyperpolarization causes lengthening
- Depolarization causes shortening
- change in length modifies the stiffness of the basilar membrane (sharpens/amplifies sound)
Olivary nuclei
- cochlear nuclei relay sound information to the contralateral AND ipsilateral superior olivary nuclei
Superior olivary nucleus
- main localization nucleus for sound
- 2 divisions
lateral superior olive
- processes intensity differences
- loud vs. quiet
medial superior olive (MSO)
- produces latency differences
- when is the sound coming (first, second, third, etc)
binaural cues
signal sound location
interaural intensity differences
difference in loudness at the 2 ears
interaural latency differences
difference between the 2 ears in the time of arrival of sounds
duplex theory
sound localization requires processing of both intensity and latency differences
tonotropic organization
- all levels of auditory pathway have this
- arranged in a map according to the frequencies in which they respond
auditory cortex
- main activation is in the A1 on the superior temporal lobes
- dorsal stream and ventral stream
dorsal stream
- toward top
- in parietal lobe
- spatial location
- “where”
ventral stream
- toward bottom
- in temporal lobe
- may analyze components of sound
- “what”
heschl’s gyrus
- portion of auditory cortex that first processes music
- larger in musicians
- more strongly activated by music
amusia
- an inability to discern tunes (tone deafness)
