the auditory system (2.3)

Question 1

amplitude vs frequency vs pitch

Answer 1

amplitude: loudness
frequency: peaks per second
pitch: complexity, timbre (quality of sound)

Question 2

natural sounds

Answer 2

complex patterns of vibrations

Question 3

Fourier analysis

Answer 3

the mathematical procedure that breaks a natural sound down into its component sine waves

Question 4

male voice vs female voice

Answer 4

male: 100 spacing
female: 200 spacing

Question 5

sound propagation

Answer 5

auditory canal -> eardrum (tympanic membrane) -> ossicles vibrate -> oval window vibrates -> fluid in cochlea set in motion -> vibrations of fluid dissipated at round window -> organ of Corti

Question 6

cochlea

Answer 6

divided into three chambers (scala) by Reissner’s membrane (top) and the basilar membrane (bottom); contains the organ of Corti (auditory receptor organ); in-and-out motion creates an up-and-down motion of the middle chamber

Question 7

basilar membrane

Answer 7

base has low mass and high stiffness (guitar string) and likes high frequencies; apex at the top; job is to figure out what kind of frequencies are there (don’t know what made it or where it came from); sets up tonotopic organization

Question 8

number of inner vs outer hair cells (organ of Corti)

Answer 8

inner: 3,500
outer: 14,000

Question 9

stereocilia

Answer 9

on the upper surface of hair cells near the tectorial membrane; up-down motion of basilar membrane converted to side-to-side motion

Question 10

mechanotransduction

Answer 10

conversion of mechanical stimulus to an electrical or chemical signal; inner hair cells release transmitter onto axons of auditory nerve (direct transduction from side-to-side motion); K+ flows in

Question 11

transmission (direct or indirect)

Answer 11

indirect

Question 12

auditory cortex

Answer 12

located in the temporal lobe; includes a core (A1) and up to 10 belt (secondary) regions

Question 13

superior olive

Answer 13

in the pons; tells you which ear the sound comes from (intensity and delay); push-pull processing

Question 14

medial geniculate nucleus (MGN)

Answer 14

in the thalamus; pitch perception (what made the pitch)

Question 15

areas of association cortex where auditory signals are conducted (2)

Answer 15

posterior parietal cortex (auditory interacting with visual system), prefrontal cortex (thoughts, actions, emotions)

Question 16

posterior vs anterior pathway

Answer 16

posterior: locating sounds (“where”); preparation for action
anterior: identifying sounds (“what”)

Question 17

McGurk effect

Answer 17

vision can affect the way sounds are perceived

Question 18

unilateral vs bilateral lesions of auditory cortex

Answer 18

unilateral: disrupts ability to localize sounds in contralateral hemifield
bilateral: localization and pitch discrimination

Question 19

conductive vs nerve deafness

Answer 19

conductive: damage to ossicles
nerve: damage to cochlea or auditory nerve; loss of hair cell receptors