Audition-Signal Encoding

Question 1

Three frequency groups

Answer 1

low: 15-500 Hz, middle: 500-5000 Hz, high: 5-200 kHz

Question 2

path of auditory information

Answer 2

spiral ganglion– (auditory nerve) –> ventral cochlear nucleus-> superior olive– (lateral lemniscus) –> inferior colliculus -> thalamus -> auditory cortex

Question 3

tonotopy

Answer 3

location of vibration on basilar membrane depends on tone. certain tones then project onto certain sprial ganglion and certion portions of the cortex (like labeled line coding)

Question 4

how are sounds generally coded for across the basilar membrane?

Answer 4

Question 5

coding for low frequencies

Answer 5

APs are locked in with the sound wave; the frequency of the sound wave = frequency of sprial ganglion firing

Question 6

coding for middle frequencies

Answer 6

labeled line and phase locking: high rate of sound waves, APs in a single neuron cannot keep up bc of refractory period, phase locking across a population, by looking at many across a population we can see the frequency of the sound wave

Question 7

coding for high frequencies

Answer 7

not precise, too many to keep up with, random, labeled line

Question 8

intensity/ loudness: depolarization and auditory nerve

Answer 8

louder = higher amplitude = more movement of membrane = more depolarization (but not more hyperpolarization)

higher amplitude = more thresholds are reached = more auditory nerve cells actiavted

Question 9

intensity/ loudness: number of nerves activated across tonotopic map

Answer 9

louder sounds have higher amplitudes so more cells around the main tone must move, causes more activation

Question 10

location: horizontal plane

Answer 10

low: intraoral time delay or phase shift (difference in time between first and second ear hearing it)
middle: intensity differences
high: can’t tell

Question 11

location: vertical plane

Answer 11

sound bounces off pinna/ reflects in different directions causing delays