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38 Cards in this Set
- Front
- Back
psychophysics vs psychoacoustics |
psychophysics: how we perceive physical stimulus psychoacoustics: how we perceive sound |
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threshold |
stimulus that produces an arbitrary, but defined, level of performance |
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Method of constant stimuli |
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 |
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method of limits |
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 |
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method of adjustment |
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 |
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uses sequential ascending and descending presentations of stimuli |
method of limits and method of adjustment |
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3 methods of threshold |
method of adjustment, method of limits, method of constant stimuli |
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Response Bias |
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 |
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catch trials |
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 |
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receiver operating character analysis |
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 |
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ROC Curve Conservative vs. liberal |
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 |
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hit correct rejection miss false alarm |
hit: signal, response correct rejection: no signal, no response miss: signal, no response false alarm: no signal, response |
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2 alternative forced choice (2 AFC) |
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 |
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masking |
interference in perception of one stimulus due to the presentation of another stimulus. any noise that interferes with your ability to hear a signal. |
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signal or probe |
stimulus you are trying to hear |
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masker |
sound that is doing the masking the other sound |
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quiet threshold |
absolute threshold for signal, probe presented alone |
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masked threshold |
threshold for signal, probe when presented with masker |
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amount of masking |
difference between quiet threshold and masked threshold masking always increases threshold` |
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true simultaneous |
signal presented midway through masker |
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forward fringe |
signal and masker start at same time , masker continues |
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backward fringe |
masker starts first, ends at the same time |
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forward masking |
period between masker then signal signal increase, masker will be less, not 1:1 level of auditory nerve: peripheral process dichotic doesn't work |
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backward masking |
signal break then masker causes not well understood more effective than forward monotic: same ear dichotic: different ears level of brainstem: central process |
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Relative Effectiveness of different types of masking |
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. |
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tone on tone simultaneous masking |
more difficult when masker is closer in frequency lower frequency, not much masking signal higher in frequency than masker, more intensity |
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pure tone maskers and narrow band noises |
may have narrow spectrums and will produce narrow regions of masking similiar to tone-on-tone higher frequencies masker to higher extent |
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broadband noise |
lots of frequencies across spectrum, masking for broad range of frequencies |
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amount of masking depends on |
timing of masker intensity frequency bandwidth |
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Temporal Resolution |
ability to follow rapid changes in a sound signal longer, easier to hear, not as intense |
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auditory nerve response to rapid change |
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) |
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sensitivity-resolution tradeoff |
extend integration time to improve sensitivity (ability to hear), you lose resolution (following rapid changes) |
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spectral splatter |
over time, want longer period of time one frequency |
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measure temporal resolution |
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 |
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modulation depth |
lowest modulation depth that we can detect a change |
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AM detection as a function of modulation rate |
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 |
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multiple integrators |
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 |
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multiple looks |
good temporal resolution because we use memory to integrate sound energy |