Cd 351 Exam 3

Front 1

psychophysics vs psychoacoustics

Back 1

psychophysics: how we perceive physical stimulus

psychoacoustics: how we perceive sound

Front 2

threshold

Back 2

stimulus that produces an arbitrary, but defined, level of performance

Front 3

Method of constant stimuli

Back 3

randomly present different intensity levels of stimuli, listener responds to stimuli, record answers

not sequential; random

Pros: easy to administer, provide precise estimate of threshold

cons: need to know threshold in advance, lots of trials, time consuming

Front 4

method of limits

Back 4

adaptive, start with level listener can hear, present levels lower and lower until cannot hear

sometimes start where easily heard, sometimes where can't hear, sequential

Pros: efficient because can 'focus' stimuli near threshold, giving threshold fewer trials, don't need threshold to start

cons: 'false' responses cause errors in estimating threshold

bias: anticipation and habituation

Front 5

method of adjustment

Back 5

subject controls stimulus instead of investigator, increase dial until hear sound, then decrease until don't hear, sequential

more intensity for high frequency

pros: easy, intuitive appeal

cons: results can be unreliable

bias: hard to tell if you heard sound at threshold

Front 6

uses sequential ascending and descending presentations of stimuli

Back 6

method of limits and method of adjustment

Front 7

3 methods of threshold

Back 7

method of adjustment, method of limits, method of constant stimuli

Front 8

Response Bias

Back 8

listerer's tendency to say 'yes I heard that'

anticipation: anticipating sound, hitting button early

habituation: stopped hearing sound, don't realize, keep pushing button

hard to tell if you heard sound at threshold

Front 9

catch trials

Back 9

present trial with no sound, does person say they hear it

pros: simple, provides info about bias, provides info regarding how reliable the threshold is

cons: doesn't provide way to adjust threshold to correct for bias

Front 10

receiver operating character analysis

Back 10

assumes when you are close to the threshold, sometimes no sound sound like something

assumes that the person's threshold is influenced by both sensitivity and bias

pros: complete and bias-free measure of sensitivity

cons: time consuming

Front 11

ROC Curve

Conservative vs. liberal

Back 11

conservative: only hit button if you are 100% positive= low hit rate, low false alarm

liberal: respond even if you think you heard something = high hit rate, high false alarm

Front 12

hit

correct rejection

miss

false alarm

Back 12

hit: signal, response

correct rejection: no signal, no response

miss: signal, no response

false alarm: no signal, response

Front 13

2 alternative forced choice (2 AFC)

Back 13

play 2 test intervals, one with sound one with no sound

listener picks interval where sound was present, bias applies equally to both intervals and cancels out

pros: bias-free, combines with other methods

cons: technical details

Front 14

masking

Back 14

interference in perception of one stimulus due to the presentation of another stimulus. any noise that interferes with your ability to hear a signal.

Front 15

signal or probe

Back 15

stimulus you are trying to hear

Front 16

masker

Back 16

sound that is doing the masking

the other sound

Front 17

quiet threshold

Back 17

absolute threshold for signal, probe presented alone

Front 18

masked threshold

Back 18

threshold for signal, probe when presented with masker

Front 19

amount of masking

Back 19

difference between quiet threshold and masked threshold

masking always increases threshold`

Front 20

true simultaneous

Back 20

signal presented midway through masker

Front 21

forward fringe

Back 21

signal and masker start at same time , masker continues

Front 22

backward fringe

Back 22

masker starts first, ends at the same time

Front 23

forward masking

Back 23

period between masker then signal

signal increase, masker will be less, not 1:1

level of auditory nerve: peripheral process

dichotic doesn't work

Front 24

backward masking

Back 24

signal break then masker

causes not well understood

more effective than forward

monotic: same ear

dichotic: different ears

level of brainstem: central process

Front 25

Relative Effectiveness of different types of masking

Back 25

signal and masker far apart, not much change in threshold

signal and masker get closer, threshold goes up (hear more)

you want higher threshold

1. forward fringe

2. backward fringe

3. true sim.

Front 26

tone on tone simultaneous masking

Back 26

more difficult when masker is closer in frequency

lower frequency, not much masking

signal higher in frequency than masker, more intensity

Front 27

pure tone maskers and narrow band noises

Back 27

may have narrow spectrums and will produce narrow regions of masking

similiar to tone-on-tone

higher frequencies masker to higher extent

Front 28

broadband noise

Back 28

lots of frequencies across spectrum, masking for broad range of frequencies

Front 29

amount of masking depends on

Back 29

timing of masker

intensity

frequency

bandwidth

Front 30

Temporal Resolution

Back 30

ability to follow rapid changes in a sound

signal longer, easier to hear, not as intense

Front 31

auditory nerve response to rapid change

Back 31

fibers do not fire at instant sound begins/ ends

fibers do not fire on every cycle of sound

spontaneous activity occurs when no sound is present

auditory nerve response does not follow change with perfect precision (exactly what signal is doing)

Front 32

sensitivity-resolution tradeoff

Back 32

extend integration time to improve sensitivity (ability to hear), you lose resolution (following rapid changes)

Front 33

spectral splatter

Back 33

over time, want longer period of time

one frequency

Front 34

measure temporal resolution

Back 34

duration discrimination: duration between 2 signals, very acute, threshold: shortest duration difference

gap detection: increase frequency, gap narrower, threshold: narrowest gap

amplitude modulation detection: how much do you have to modulate amplitude for listener to tell its been modified

Front 35

modulation depth

Back 35

lowest modulation depth that we can detect a change

Front 36

AM detection as a function of modulation rate

Back 36

temporal modulation transfer funtion (TMTF)

higher frequencies, big changes in depth

good at AM detection up to 50-60 Hz mod. rate

50-60 Hz= 17-20 ms/cycle of modulation

Front 37

multiple integrators

Back 37

good temporal resolution because neural fibers have different integration times

AN fibers receiving info from inner HC and going to brain

200 ms: good for detecting sound

500 ms: good for detecting gap

Front 38

multiple looks

Back 38

good temporal resolution because we use memory to integrate sound energy