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Psych year one > hearing > Flashcards

hearing Flashcards

1
Q

what is a sound?

A
  • Sound arises from the movement of vibrations of an object
  • This triggers a soundwave/movement which squeezes air molecules together and pulls them apart
  • This pressure wave travels and spreads outwards from the source to the listener.
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2
Q

what is the y and x axis of a waveform and how is it presented ?

A

y axis = amplitude
x axis = time
as a wave

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3
Q

what is the y and x axis of a spectrogram and how is it presented ?

A

y axis = frequency
x axis = time
as a line

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4
Q

what is amplitude?

A

the intensity or loudness of a sound

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5
Q

what is period of a wave ?

A

it is the frequency/pitch of a wave

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6
Q

how is pitch expressed

A

as hertz (Hz) this is the number of a time a period is repeated every second

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7
Q

what does complexity of a sound refer to?

A

its timbre

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8
Q

how is loudness measured?

A

in decibels

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9
Q

explain the decibel scale

A

starting at 0 is the human threshold up to 140 which would really hurt a person ears (airplane taking off)

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10
Q

what is timbre?

A

timbre is the difference between a sound that has the same pitch and loudness
for timbre a sound must be complecx and have various tones

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11
Q

what does each complex tone have?

A

a fundamental tone
multiple frequencies referred to as harmonics

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12
Q

do harmonics in a compex tone have to have the same amplitude?

A

no

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13
Q

what is the relationship between the fundamental harmonic and the other harmonics in a complex tone?

A

the other harmonics are a multiple of the fundamental tone
so if the fundamental tone has Hz of 200 the second harmonic will be 400 Hz

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14
Q

areas of the ear

A

outer
middle
inner

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15
Q

outer ear name

A

pinna

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16
Q

describe the middle ear

A
  • the middle ear is air filled
  • three bones called ossicles
  • ear drum
  • equalises pressure betwen the middle ear and the outside
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17
Q

how do the three ossicles function

A

they are attached as a lever hitting the ear drum with vibrations which then need to be replicated by the cochlea

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18
Q

describe the cochlea

A

its a spiral shaped system that is fluid filled within the inner ear

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19
Q

what do the ossicles do to vibrations

A

they have to amplify sounds we hear by 20x so that the cochlea can replicate the sound. this is because the cochlea is fluid filled it needs louder vibrations to replicate

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20
Q

what is the stapedial reflex

A

muscular reflex in the ear which contracts the bones to come away from the oval window so that the loud vibrations aren’t amplified before going to the cochlea which prevents damage.

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21
Q

what is the basilar membrane?

A

strip of flesh - vibrates when the stapes (3rd bone) moves the fluid in the ear - narrow at base and wide at the apex (floppy and thin) the bottom vibrates with high frewuncy sounds the top is low frequency

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22
Q

the top of the basilar membrane vibrates with what frequencies?

A

low frequencies

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23
Q

the cochlea acts as a

A
  • frequency analyser, converts enegrgy at different frequencies into neural activity in different fibres of the auditory nerve
  • top is the chamber sound goes up theres a hole then into the bottom chamber.
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24
Q

what is the organ of corti?

A
  • sits on top of the basilar membrane
  • full of neurons and sensory cells
  • one row of inner hair cells and 3 rows of outer hair cells
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25
Q

what od the outer hair cells of the organ of corti do?

A

outer hair cells - put energy into the basilar membrane and amplify sounds

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26
Q

what do the inner hair cells of the organ of corti do?

A

detect the movement of the basilar membrane

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27
Q

tectorial membrane

A

inner hair cells are crushed against and bent this may trigger an actjon potential.

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28
Q

what is the cochlear nucleus

A

a relay struction in the brain stem - sends neural activity to other nuclei in brain stem for analysis. last station where ears are independent.

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29
Q

what is the superior olive?

A

merges the ear together, analyses the location of the sound.

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30
Q

what dopes the primary auditory area in the cerebral cortex do?

A

nalyses higher-order features of sounds, including their spectral shape. This happens later in auditory pathway than analyses of location and pitch because it is less reliant on precise timing.

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31
Q

what is frequency selectivity?

A
  • the ability to separate sounds with different frequencies that occur at the same time.
  • when sounds have a similar timbre it is difficult to sperate them because they activate a similar area of the basilar membrane.
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32
Q

what is laser interferometry?

A

measures the basilar membrane selectivity by placing a tiny glass bead on the basilar membrane of an anaesthetised animal and then beams a lazer on the glass ball. then play different tones and measures its vibrations and motion.

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33
Q

psychoacoustic demonstration of frequency selectivity

A

tight headphones if they can hear a tone.

play tone with background noise and see at what point they can discriminate from two frequencies.

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34
Q

How close can the noise be to the target frequency for us to hear them seperatley?

A

this can be researched in the lab psychoacoustically

test tone at a fixed level

masker tone you have to ignore - this will be maniuplated so taht its impossiblw for u to hear the test tone

adjusted until we cant heat test tone

test = 4000Hz

the closer the masker is to the frequency tone, the lower the level of the masker needed to mask the test tone.

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35
Q

how does frequency selectivity benefit speech?

A

sounds are so similar but because we can detect the diffrent pitches it allows us to know what is being said.
frictivie sounds have higher frequencies for example

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36
Q

what is mimiumum of a speech sound we need to here to disginuish between two speech sounds

A
  • we only need to hear the first and second formant of a sound for our basilar membrane to distinguish between sounds
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37
Q

what is a formant

A

the amplified (peaks) of frequencies within a vowel

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38
Q

what is the bottom up effect of hearing

A

basilar membrane etc

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39
Q

what are the five top down effects on hearing?

A

Ganong effect, phoneme restoration, sound and word reduction, sinewave speech and McGurk effect.

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40
Q

what is the ganong effect and example?

A

the tendency to hear an ambigous word as a word we already know effect of lexical knowledge on phoneme identification

play g - k on a continuimm

if sound is g theyll get 0% k responses but this increases as you go

but if you add iss to the end of the letters hearing the k starts earlier bc kiss is a word not giss.

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41
Q

what is phoneme restoration?

A

when we trick our auditory system into hearing a word we exepect even if it is said wrong.

e.g., approximatley without the l we would still hear the full word

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42
Q

sound and word reduction

A

words can be acoustically reduced but we have semantic expectations and can hear words

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43
Q

McGurk effect

A

our audiorty information changes as to what is in the visual

sound says bah but a person looks at someone saying fah and we believe theyre saying bah and that’s what we hear

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44
Q

sinewave speech

A

speech signal in which the formants of speech have been replaced with pure tone tracking the intensity modulations of those formants over time.

this is phonological, lexical, syntactic, semantic knowledge. Fast recalibration.

45
Q

where do the top down phenomena occur in the brain?

A

occurs in the cortex

looked at brain activation during the Gangong effect and found that auditory primary cprtex, superior temporal grysu interacts with other areas superior medial gyrus where semantic knowledge is.

the area that deals with long term lexical info seems to have a top down effect on the primary auditory cortex.

46
Q

brain activation during ganong effect

A

found that auditory primary cprtex, superior temporal grysu interacts with other areas superior medial gyrus where semantic knowledge is.

47
Q

auditory illusions in schizophrenia

A

evidence suggests the primary auditory cortex is activated in patients with psychosis

It is either deactivated or activated

48
Q

experiment on inattentional deafness (when youre focused and and have selective auditory attention)

A

the recorded activity of the brain stem in a task - they listened to a tone then a deviant tone every time they heard this had to press a button. they also had to do a task (easy/medium/hard). you press the button of an image before or 2/3 images before. nothing changes in what you are hearing, the more difficult the visual task is the less involved the auditory system is in the brain stem.

49
Q

brain evidence of slective attention

A

top-down effect of superior olive in the brain stem on the cochlea. During the selective attachment there’s some evidence that the response of hair stells in the cochlea are affected.

reflex to protect your hearing —> brain stem tells cochlea to reduce sensitivity.

50
Q

how many people are born deaf?

A

1 in 1000 have it a birth

51
Q

how do we test peoples hearing?

A
  • in a quiet envrionment
  • the audiologist will press a pure tone that most people should be able to hear, if you hear it you press a button
  • then the audiologist will turn the intensity down
  • until they can no longer hear
  • up and down to establish threshold
  • average your loss of thresholds - PTA (pure tone average)
52
Q

deafness clnical bands

A

20db normal
40-70 moderate
95 profound impairment

53
Q

what is conductive hearing loss?

A

loss of mobility of the bones in the middle ear

they amplify vibrations of the oval windows but if these bones don’t work then they cant amplify this sound

what makes the bones not work = is fluid build-up so ossicles cant move as fast as they usually do (otitis media)

fixation of the stapes (bone connected to oval window) arthritis of bone in era.

54
Q

what are the causes of cochlear hearing loss?

A

genetics

ototoxicity

noise

decreased oxygenation

55
Q

damage to hair in the ear effects…

A

the cochlear

56
Q

what are the 4 impairments due to ear hair damaged?

A
  1. loss of sensitivity to quiet sounds
  2. loss of frequency selectivity - important to detect difference between speech sounds etc
  3. loudness recruitment
  4. reduced sensitivity to temporal fine structure
57
Q

what does loss of frequency selectivity refer to?

A

this can be tested in a lab with people who have deafness in one ear, they play a test tone, you have to detect this, mask tone vary intensity and freqnecy and see how long it is until you can no longer hear test tone

58
Q

what does loudness recruitment refer to?

A

reduced tolerence of loudness - this means that hearing loss is different at different intensities and it is not linear for example hearing a sound at 60 DB and matching it to 30 DB doesn’t mean 90 DB will be matched to 60 DB as sound is louder the lines converge to healthy hearing and will begin to match them and auditory threshold is the same for deaf and non deaf people

pain threshold hasnt increased

59
Q

what is TFS?

A

the tone of the sound

60
Q

what is the temporal envelope?

A

quick changes in sensitivity

61
Q

what does reduced sensitivity to TFS mean?

A

TFS is important for accurate pitch perception.

Difficulties in processing TFS make it harder to hear what one person is saying when other people are speaking at the same time.

62
Q

what do hearing aids do?

A

hearing aids amplify sounds to the inner hair cells that conduct movement on the basilar membrane this is why they cannot help for profound hearing loss because the inner hair cells are damaged and cannot detect the sound of the basilar membrane

63
Q

what can hearing aids not do?

A

cant improve TFS
cant improve loss of frequency selectivity

64
Q

how do cochlear implants work?

A

a string of electrodes bypass the middle ear, straight to the cochlear, and you push it in around the cochlear.

they filter the acoustic signal into 8 or more frequency bands

lowest 350 HZ

highest 5400 HZ#

the temporal envelope is extracted and conveyed to auditory fibers by varying amplitude of electrical pulses

pulses are transmitted by electrodes to the appropriate place in the cochlear for each frequency band

65
Q

who has the most successful experience of cochlear implants?

A

children before they age of 4
people who are motiavted
have residual hearing

66
Q

should we implant both ears?

A

yes
- guaranteed to implant better ear
- insurance
-spatial hearing
no
- operate on both ears
- cost

67
Q

what is the effect of outer hair cells amplifying movementof basilar membrane?

A

It increases the sensitivity of the ear to low-intensity sounds
It sharpens the frequency selectivity of the basilar membrane

68
Q

what happens if out hair cells are damaged?

A

It decreases sensitivity to low-intensity sounds (pure-tone thresholds are raised)
The ear is less able to separate energy at one frequency from energy at adjacent frequencies (frequency selectivity decreases)

69
Q

what is the difference between TFS and frequency selectivity

A

FS deals with the intricate timing details of sound and fluctuations in sounds, frequency selectivity deals with how the ear separates and processes different pitches.

70
Q

what plain is azimuth

A

horizontal plane with azimuth is left - right
azimuth 0 is straight in front of you
-180 and + 180 are straight at the back they’re the same

71
Q

medial plane

A

up - down - vertical plane
elevation to describe it
elevation + is above - down below

72
Q

how to establish someone’s minimum audible angle? (MAA)

A
  • start with a refernce sound straight head of you
  • second tone to left/right
  • decide if tone has moved to left or right
  • change angle and then detect when can no longer detect wnere its coming from
73
Q

what is our ability to detect where a sound is coming from dependent on?

A

frequency

74
Q

what frequencies are we better at detecting where they come from in azimuth plane?

A
  • low frequency
  • azimuth 0/1
  • starts to improve again at higher frequencies
75
Q

when are we worse at detecting where sounds are coming from in the azimuth plane?

A
  • when the sounds are coming from non-frontal locations
  • MAA is larger around 1500Hz
76
Q

how do we know where sound is coming from?

A

interaural timing difference
ITD and ILD interaulral level difference

77
Q

what is the speed of sound?

A

343 meters per second

78
Q

what is interaural level difference (ILD)?

A
  • intensity of the sound
  • there is a head shadow
  • the head shadow shields the sound from getting to the opposing ear, absorbs energy maing sound less when it gets to other ear
  • the difference between the sound hitting one ear and the sound hitting the other ear is called the ILD
79
Q

how much faster is sound going to the right ear if the azimuth is in 90+?

A

650 microseconds

80
Q

what is the smallest difference we can detect in the ITD?

A

10 microseconds

approx one degree from straight ahead

81
Q

what frequencies does ILD help us detect where a sound is coming from?

A

high frequencies
useless at low frequencies

82
Q

why is ILD better at detecting higher frequencies?

A
  • high frequencies bound off
  • low freqycnies wrap around object
  • distruptive for high not for low
83
Q

what is the smallest ILD that listeners can distinguish from and ILD at 0 dB?

A

1dB

84
Q

WHAT ARE THE TWO CUES TO LOCALISTAION OF SOUND?

A

ILD - interaural level difference
ITD - interaural time difference

85
Q

what frequency are timing differences detected at?

A

low frequencies

86
Q

what principle explains why we ITDs are unambiguous at low frequencies?

A

pair similiar co occurring patterns principle

87
Q

what dos the pairing similiar co occurring frequencies mean for the ITD cue?

A
  • works only for low frequencies
  • because, waves pair with each other and you can detect which go together
  • at higher frequencies pairing become ambiguous and misleading
  • dont know pairs - dont know what comes first at higher frequencies ( left or right0
88
Q

how to work our period (T) from pitch (f)

A

T = 1/ f

89
Q

what is Lord Rayleighs duplex theory?

A
  • ITD for low
  • ILD for high
  • alternate allows us to localise sound
90
Q

what does Rayleighs duplex theory apply to?

A
  • pure tones
  • the rules dont apply for complex tones, which is what we hear most of the time
91
Q

why does the pairing similiar co occuring patterns principle work for complex tones in the ITD cue?

A
  • works for both high and low frequencies in complex tones
  • because we pair similar patterns and wave shapes
92
Q

what is considered a low frequency

A

less than 750Hz

93
Q

what is a high frequency?

A

1500 hz

94
Q

do we use ITD OR ILD MORE?

A
  • ITD bceause they are more powerful and work over a wider range.
95
Q

what is the delay line and coincidence detector theory?

A
  • left ear and right have action potential
  • it is triggered when they both pass the same coinicidence detctor
  • there is a detector for each different angle in azumith
  • so when action potnetial goes into roight ear first at 30 degress for example, it will trigger that coincidence detctor to tell us its in the irght ear
96
Q

what animal has delay lines and coincidence detectors been found in?

A

birds and barn owls

97
Q

what system are mammals more likely to use?

A

opponent process system

98
Q

what is the opponnent porcess system?

A
  • there are two channels
  • one tuned for left auidtory space and one for right
  • we do different in response in third channel (right - left)
  • works our where sound is on azimuth plane
99
Q

how does the pinna help us decide if a sound is coming from behind or in front of us?

A
  • pinna acts as a shadow
  • high frequencies are reflected off it
  • since this doesnt happen with higher frequencies in front of us its a cue that sound is behind
  • pinna oost and reduced energy at different frequencies
  • soundwaves delayed at pinna go in ear drum, delay vary with elevation alog us to know the elevation
  • pinna-speceifi modulations determine elevation
100
Q

when does pinna reflection work ?

A

with familiar sounds

101
Q

prosthetic pinna experiment?

A
  • prosthetic pinna
  • laser, point where sound is coming from
  • 16 different elevations
  • found - hard to find different sounds
  • lost sense of elevation not azimuth
102
Q

what is pinna essential for?

A

detecting the elevation of sounds

103
Q

what happens with fake pinna for a month?

A
  • they learn elevation with new pinna, flexibility in learning elevation
104
Q

how do VR create elevation in sound?

A
  • head related transfer functions
  • recprd sounds using mannequins
  • maximise reverberations
  • simulation of pinnas
  • HRTF take everything nto account
  • played back to gamers in headphones for externalised virtual acoustic space
105
Q

how good are HRTF? experiment

A
  • company recorded HRTF
  • PP played back this in a booth
  • three groups ( headphones, loudspeaker, specific pinna HRTF headphones)
  • ground truth (not headphones) is best
  • using own pinnas is better
106
Q

what is the prescendence effect

A
  • echo suppression
  • echo supressed if it follow sound in a short period of time
  • preceeding sound is used to find location of sound
107
Q

release from informational masking

A

makining one of rthe voises an echo so one of the voices is more clear

108
Q

what animals sued echoes to benefit them ?

A
  • ats and dolphins
  • use echoes to locate food
109
Q

what does primary auditory cortex do?

A

alyses higher speech getaurre susch as spectoral shape

Psych year one (19 decks)

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