Senses: Audition

Question 1

What range of frequencies are humans especially good at detecting?

Answer 1

2000-5000 CPS

Question 2

What range can bats hear?

Answer 2

100000 CPS

Question 3

External ear mechanisms

Answer 3

also called the pinna or external auditory meatus.

Question 4

Middle ear mechanisms

Answer 4

Tympanum and Ossicles

Question 5

Pinna (Pinnae)

Answer 5

pinnae are directional and perform early sound processing. sound waves are guided into the ear canal, which leads to the middle ear.

Question 6

Tympanum

Answer 6

aka the eardrum, a taut membrane that seal the end of the ear canal. it vibrateswhen struck by soundwaves and converts sound energy into kinetic energy. for the tympanum to vibrate, the middle ear has a eustachian tube leading to the oral-nasal cavity, which is how ear infections get in

Question 7

Ossicles

Answer 7

there are 3 of them: malleus, incus, and stapes, they form a chain that mechanically couple the vibrating tympanum to the inner ear.

Question 8

Middle ear muscles

Answer 8

Tensor tympani - a minute muscle connected to the malleus connecting the ossicle to the tympanum

Stapedius - connects the stapes to the floor of the middle ear

Question 9

Modulation

Answer 9

occurs within 200msec of a loud noise. if the noise is coming from you, the gain control switches on. if this didnt happen, your voice would be extremely loud to you

Question 10

Sound emitters

Answer 10

sound emitters produce compressions and rarefractions in air

Question 11

frequency

Answer 11

the time interval from peak to peak

Question 12

amplitude

Answer 12

the peak height of the sound wave, aka loudness

Question 13

harmonics

Answer 13

multiples of the frequency of an emitter

Question 14

timbre

Answer 14

the unique sound of an emitter comprised of the frequency and harmonics

Question 15

doppler shift

Answer 15

where velocity is added to the emitter, creating volume

Question 16

resonance

Answer 16

where area affects which emitters are expressed more (more area, lower emitters, less area, higher emitters)

Question 17

inner ear mechanisms

Answer 17

cochlea and organ of corti

Question 18

cochlea

Answer 18

rolled tube containing three channels filled with gel fluids. vibrations from the tympanum are communicated to the endolymph

Question 19

gel fluids in cochlea

Answer 19

endolymph and perilymph

Question 20

organ of corti

Answer 20

the most important part of the cochlea, consists of:
basilar membrane - divides the tubes of the cochlea
tectorial membrane - another divider
special receptor cells called hair cells

Question 21

inner hair cells

Answer 21

up to 3500 CPS, near the basilar membrane. when stimulated, releases glutamate onto auditory nerve fibers

Question 22

outer hair cells

Answer 22

up to 12000 CPS, similar to inner hair cells, releases ACh and influenced by GABA

Question 23

how does auditory system work?

Answer 23

ossicles transmit vibrations to the fluid in the cochlea
waves cause basilar membrane to ripple
depending on the frequency, the amplitude of the wave is exaggerated at a specific location on hte basilar membrnae due to resonance

Question 24

what are the 4 types of nerve fibers

Answer 24

IHC afferent - IHC to brain
IHC efferent - brain to IHC
OHC afferent - OHC to brain
OHC efferent - brain to OHC

Question 25

what are the major centres of the auditory pathway

Answer 25

cochlear nuclei - brainstem, recieves and integrates inputs from both cochlea inferior colliculus - midbrain, tuning/spacial localization in some species medial geniculate - part of thalamus, projects to auditory cortex

Question 26

place theory

Answer 26

percieved pitch corresponds to location on basilar membrane that is most strongly activated

Question 27

volley theory

Answer 27

pitch is a function of hte rate of firing in auditory fibres

Question 28

vestibular system

Answer 28

mechanism for detecting changes in head position. there are 3 semicircular canals: fluid filled where movement of the heead causes fluid to circulate ampulla where hair cells translate movement in neural signal otoliths overlie haricells and amplify the effect