chapter 11: hearing

Question 1

what is the difference between the physical and the perceptual definition of sound

Answer 1

physical: pressure change
perceptual: experience

Question 2

when does a sound stimulus occur

Answer 2

mov or vibrations of an object causes pressure change in air/water or other elastic medium

Question 3

explain the compression and the rarefaction process

Answer 3

compression: push surrounding air molecules together, density ↑
rarefaction: air molecules spread out to fill increased space, density ↓

Question 4

what is a sound wave

Answer 4

pattern of alternating high and low pressure regions
- speed of 340meters/sec

Question 5

true or false? when sound causes air to move, the air molecules travel further and further away from the sound stimulus

Answer 5

false, they move back and forth but stay in the same place

Question 6

what is a pure tone

Answer 6

changes in air pressure that occur in a pattern called sine wave

Question 7

differentiate frequency and amplitude

Answer 7

frequency: number of cycles per second
amplitude: size of pressure change

Question 8

sound frequency are measured in … and higher frequencies are associated with higher …

Answer 8

Hertz (Hz)
pitch

Question 9

sound amplitude are measured in … and the amplitude of a sound is associated with the …

Answer 9

decibel (dB)
loudness

Question 10

what is a periodic waveform

Answer 10

waveform that repeats

Question 11

what is called the repetition rate of a waveform

Answer 11

fundamental frequency

Question 12

the first harmonic is the frequency equal to the fundamental frequency. how are higher harmonics calculated?

Answer 12

multiples of the fundamental frequency
- 2nd harmonic is frequency x 2

Question 13

describe the frequency spectra

Answer 13

line position indicates frequency (horizontal axis)
line height indicates harmonic’s amplitude

Question 14

In a complex tone, removing a harmonic doesn’t change the rate of repetition, only the waveform. Why is that

Answer 14

when the fundamental is removed, the spacing remains so there is still info in the waveform indicating the frequency of the fundamental

Question 15

what is the equation used to transform sound pressure level into decibels

Answer 15

dB = 20 x log10 (p/po)
where p = pressure of sound
po = reference pressure

Question 16

what procedure was used to determine the relationship between level in decibels and loudness

Answer 16

magnitude estimation

Question 17

in the audibility graph, indicate what the audibility curve, the auditory response area, the threshold of feeling, and the equal loudness curve represent

Answer 17

audibility curve: threshold for hearing
aud resp area: tones we can hear
threshold of feeling: when tones become painful and can cause damage
equal loud curve: diff frequencies, same loudness

Question 18

the lowest and the highest note on the piano is represented by how many hertz

Answer 18

low: 27.5Hz
high: 4186Hz

Question 19

define tone height

Answer 19

perceptual experience of increasing pitch that accompanies increases in a tone’s fundamental frequency

Question 20

define tone chroma

Answer 20

different octaves of the same note
- fundamental frequencies that are multiple of two

Question 21

what is the effect of the missing fundamental

Answer 21

when pitch remains the same, even when the fundamental or other harmonics are removed

Question 22

what is a sound’s timber

Answer 22

quality that distinguished between two tones that have the same loudness, pitch and duration, but still sound different

Question 23

what are the two things a sound’s timber depends on

Answer 23

1. steady-state harmonic structure
2. attack and decay of the tone’s harmonic

Question 24

define what are a tone’s attack and a tone’s decay

Answer 24

attack: buildup of sound at the beg of the tone
decay: decrease in sound at the end of tone

Question 25

what are aperiodic sounds

Answer 25

waveforms that do not repeat

Question 26

name the three tasks the auditory system accomplishes as sound enters the ear and culminates inside the ear

Answer 26

1. delivers sound stimulus to receptors 2. transduces stimulus from pressure change to electrical signal 3. process electrical signal

Question 27

what are the structures in the outer ear

Answer 27

1. pinnae 2. auditory canal 3. tympanic membrane (eardrum)

Question 28

what are the two functions of the auditory canal

Answer 28

- protects middle ear structures - enhance intensities of sound: resonance

Question 29

explain the physical principle of resonance

Answer 29

sound waves that are reflected back from the closed end of the auditory canal interact with sound waves that are entering the canal

Question 30

what do we call the frequency that is reinforced the most

Answer 30

resonant frequency

Question 31

name the structures in the middle ear

Answer 31

ossicles: malleus, incus, stapes oval window

Question 32

why is it necessary to enhance sound intensities from the middle ear to the inner ear

Answer 32

pressure changes in the air are transmitter poorly to the liquid in the inner ear

Question 33

how do ossicles help transmit the vibrations from the middle ear to the inner ear

Answer 33

1. concentrates vibration of the large tympanic membrane onto the much smaller stapes 2. creates lever action

Question 34

name the structures in the inner ear

Answer 34

cochlea - scala vestibuli - scala tympani - cochlear partition

Question 35

describe the organ of Corti in the cochlear partition

Answer 35

- rests on basilar membrane - 1 row of inner hair cells and 3 rows of outer hair cells - stereocilia of tallest row of outer hair cells embedded in tectorial membrane

Question 36

how does vibration cause bending of the stereocilia

Answer 36

- back and forth mov of oval window transmits vibration to liquid in cochlea - basilar membrane moves - organ of Corti vibrates up and down - tectorial membrane move back and forth - stereocilia of outer hair cells embedded bend - other hair cells bend to pressure waves

Question 37

where does electrical signals occur

Answer 37

in inner hair cells

Question 38

how does bending of the stereocilia cause electrical signals (transduction)

Answer 38

when stereocilia bend - tip links stretch - open tiny open ion channels in membrane of stereocilia - K+ ions flow in cell, electrical signal created when stereocilia bends in other direction, inverse happens release of NT in synapse = auditory nerve fibers fire

Question 39

when the pressure increase, towards which direction does the stereocilia bend

Answer 39

to the right

Question 40

define phase locking

Answer 40

property of firing at the same place in the sound stimulus

Question 41

for high-frequency tones, why don't nerve fiber fire every time

Answer 41

needs to rest after it fires

Question 42

as the frequency increases, the place on the membrane that vibrates the most moves from the ... to the ...

Answer 42

apex; base of the oval window

Question 43

what is called the map of frequencies

Answer 43

tonotopic map

Question 44

how do outer hair cells function as cochlear amplifiers

Answer 44

- ion flow causes mechanical changes in cell that causes it to expand and contract - pulls stereocilia in one direction and the other - pulls on basilar membrane and increases its motion - sharpens its response to specific frequencies

Question 45

what is the place theory that explains the physiology of pitch

Answer 45

brain identifies which neurons on the basilar membrane responds the most to determine pitch

Question 46

what is the pathway from auditory nerve fiber to auditory cortex

Answer 46

cochlear nucleus superior olivary nucleus inferior colliculus medial geniculate nucleus primary auditory cortex

Question 47

in which region do signals from the left and right ear first meet

Answer 47

superior olivary nucleus

Question 48

what is the frequency-matched noise

Answer 48

noise stimulus covers the same range as pitch stimulus

Question 49

which area in the cortex is most responsive to pitch

Answer 49

anterior auditory cortex - mainly to resolved harmonics, not unresolved

Question 50

what is the difference between resolved and unresolved harmonics

Answer 50

resolved: lower harmonics can be distinguished by a peak unresolved: higher harmonics doesn't indicate individual harmonic

Question 51

between resolved and unresolved harmonics, which result in a stronger perception of pitch

Answer 51

resolved

Question 52

what are amplitude-modulated noise

Answer 52

sound stimulus that weren't associated with vibration of a particular place on basilar membrane, but still created perception of pitch

Question 53

define amplitude modulation

Answer 53

level of noise was changed = loudness of noise fluctuated rapidly up and down

Question 54

pitch perception and phase locking only occurs up to how many hertz

Answer 54

5 000

Question 55

what is one of the main cause of hearing loss

Answer 55

noise in the environment

Question 56

damage to outer hair cells results in ...

Answer 56

loss of sensitivity and loss of sharp frequency tuning

Question 57

what is presbycusis

Answer 57

hair cell damage resulting from the cumulative effects over time of noise exposure, ingestion of drugs that damage hair cells and age-related degeneration

Question 58

what is hidden hearing loss

Answer 58

people with "normal" hearing who have trouble hearing in noisy environment

Question 59

what test is used to determine if someone has "normal" hearing

Answer 59

detect faint noise in quiet room - threshold - "normal" is 0dB on audiogram

Question 60

true or false? hair cells damage are permanent after noise exposure

Answer 60

false, auditory nerve damage is permanent. hair cells recover after 8 weeks