intro to auditory neuroscience Flashcards
what is sound?
speed of sound in air
340 m/s
amplitude of sound
“sound level” or “sound intensity”
- expressed in log scale in dB sound pressure level (SPL)
frequency
- related to pitch
- expressed in hertz
- cycles per second
sound properties
- amplitude
- frequency
- phase
- timbre
phase
mostly ignored by human hearing
timbre
harmonic content
how can we change amplitude or frequency of sound?
- tuning forks (induce vibration)
- greater amplitude =
anatomy of the ear
- pinna
- auditory canal (skin and air)
- tympanic membrane (ear drum)
- auditory ossicles
- vestibular system
- auditory nerve
- cochlea
3 parts of the ear
- outer
- middle
- inner
ossicular chain
- malleus - rests on tympanic membrane (moves with vibration)
- incus
- stapes
(in middle ear, chain reaction of vibrations to move each other)
the ______ induces movement of the ______ _________ which is the communication from middle to inner ear.
stapes, oval window
the inner ear is filled with
fluid
why is fluid complicated for sound movement?
the amplitude decreases in fluid instead of air
how does the ossicular chain maintain amplitude when moving sound into fluid?
1:1.3 movement ration of amplification of the vibrations
- the stapes moves more than the malleus
tympanic membrane is larger than the oval window by a factor of ________ which increases sound wave pressure by ______
18.6x , 15x
the inner ear communicates with the
oral cavity
eustachian tube
the cochlea
- spiral structure
- made of bone
- membranes and fluids
parts of the cochlea
- base
- apex
- scala vestibuli
- scala tympani
how can the change of sound be produced in the cochlea?
- tympanic membrane vibrates
- vibrates malleus, incus, stapes,
- stapes vibrates the cochlear fluid and basilar membrane
place theory for frequency encoding in cochlea
different vibrations will cause vibrations in different locations of the basilar membrane
- high frequency is closer to base
- lower frequency is closer to apex
organ of corti
- innervated by auditory nerve fibers of CN VIII
mechanotransduction of the organ of corti
- relating of mechanical stimulus into action potentials
- have cilia (“hair cells”)
- support cells
what cranial nerve innervates the hair cells
VIII