perception 4

Question 1

what is the perceptual definition of sound?

Answer 1

sound is the experience we have when we hear

Question 2

what is the physical definition of sound?

Answer 2

sound is pressure changes in the air or other medium caused by the vibration of an object

Question 3

what is a pure tone?

Answer 3

when changes in air pressure form a perfect sinuoidal wave

Question 4

what is amplitude?

Answer 4

size of the variation in air pressure

Question 5

what is amplitude related to perception of?

Answer 5

loudness

Question 6

what is frequency?

Answer 6

the number of cycles per second

Question 7

what is frequency related to perception of?

Answer 7

pitch

Question 8

what are complex sounds?

Answer 8

combinations of different sine waves

Question 9

what do natural sounds consist of?

Answer 9

fundamental frequency with harmonics

Question 10

what are the three sub divisions of the ear?

Answer 10

outer, middle and inner

Question 11

what does the outer ear consist of?

Answer 11

pinnae
auditory canal
tympanic membrane (eardrum)

Question 12

what is the pinnae?

Answer 12

visible external parts of the ear

Question 13

what is the auditory canal?

Answer 13

tube-like structure which protects the middle ear

Question 14

what is the tympanic membrane?

Answer 14

cone shaped membrane which separates the outer and middle ear

Question 15

how do sound waves affect the tympanic membrane?

Answer 15

cause a pressure difference= vibration

Question 16

what do larger amplitude sounds result in?

Answer 16

larger vibrations

Question 17

what do higher frequency sounds result in?

Answer 17

faster vibrations

Question 18

what does the middle ear consist of?

Answer 18

small cavity containing the ossicles (smallest bones in human body)

Question 19

what are the ossicles?

Answer 19

malleus (hammer)
incus (anvil)
stapes (stirrup)

Question 20

what do the ossicles do?

Answer 20

amplify the vibrations of the tympanic membrane

transmit them to the inner ear at the oval window

Question 21

what is the main structure in the inner ear?

Answer 21

cochlea

Question 22

what does the cochlea do?

Answer 22

vibration displaces its fluid
=change in pressure which spreads across the spiral structure

Question 23

what are the three canals the cochlea consists of?

Answer 23

vestibular
middle
tympanic

Question 24

which membrane triggers auditory transduction?

Answer 24

basilar membrane

Question 25

what is auditory transduction?

Answer 25

transformation of sound waves to electrical energy, by the Organ of Corti

Question 26

how is a voltage generated in auditory transduction

Answer 26

sensitive specialised hair cells in the Organ of Corti are bent = impulses in auditory nerve cells are sent to the brain

Question 27

what scale is amplitude measured on?

Answer 27

logarithmic scale in decibels

Question 28

what is rate code? (loudness)

Answer 28

sound amplitude is coded in the firing rate of auditory nerve fibres

Question 29

how do we discriminate loudness?

Answer 29

increase in sound intensity= increase in auditory nerve rate intensity some fibres- high spontaneous rates, saturate rapidly some fibres- low spontaneous rates, saturate slowly

Question 30

what does loudness depend on?

Answer 30

amplitude frequency

Question 31

what range of pitches can humans hear between?

Answer 31

20Hz and 20,000Hz

Question 32

what is place code? (pitch)

Answer 32

sound frequencies cause vibration in specific areas along the basilar membrane

Question 33

where do low frequencies cause vibrations?

Answer 33

near the apex

Question 34

where do high frequencies cause vibrations?

Answer 34

near the base

Question 35

what is timing code? (pitch)

Answer 35

frequnecy depends on which auditory nerve fibres respond and when they respond

Question 36

what is phase locking?

Answer 36

auditory nerve responses are synchronised according to changes in pressure, up to 4000Hz

Question 37

what is pitch determined by?

Answer 37

frequency of a sound

Question 38

what is timbre determined by?

Answer 38

number, frequency and amplitudes of harmonics

Question 39

what is the missing fundamental illusion?

Answer 39

we continue to perceive a pitch as consistent with a missing fundamental frequency

Question 40

what does the missing fundamental illusion suggest?

Answer 40

brain also infers missing fundamentals- not just determined in cochlea (top down process)