Hearing Science 1 Exam 3

Front 1

Psychophysics

Back 1

the scientific study of the relationship between the physical events and the sensations to which they give rise

Front 2

absolute threshold

Back 2

minimum detectable level of a sound in the absence of any other external sounds

Front 3

difference threshold

Back 3

the smallest difference between two tones (frequencies or intensities) that you can discriminate against.

Front 4

two ways to measure threshold

Back 4

close entrance to ear canal or inside of the ear (headphones and inserts)

soundfield

Front 5

when two ears vs one ear are used...

Back 5

thresholds are about 2-3 dB lower

Front 6

threshold vary with...

Back 6

two ears vs one ear

"normal" hearing can vary as much as 20 dB +/- 0 dB SPL

frequency

age

stimulus duration ( tones under 200 ms)

Front 7

detection vs discrimination

Back 7

Absolute sensitivity: tone detection, method of constant stimuli

Differential sensitivity: discrimination between two things (frequency, intensity, etc), adaptive method

Front 8

Weber's law

Back 8

change between two stimuli that's just noticeable is proportional to the magnitude of the original stimulus (res of perception diminishes with stimulus of greater magnitude - 90 to 95 probs won't distinguish, 10 to 15 probs will!)

Front 9

Weber fraction

Back 9

change in intensity to detect change / original stimulus intensity = K

It's a constant and independent of original intensity

Front 10

stimulus features for discrimination?

Back 10

frequency, intensity, location, duration, pulsed vs continuous, ITD vs ILD, voice frequency

Front 11

Signal Detection Theory

Back 11

way to analyze decision making in the presence of uncertainty; separates factors related to uncertainty from factors related directly to sensory abilities (accounts for the fact that responses may vary from trial to trial even with the same stimulus)

Front 12

Signal Detection Theory Response options

Back 12

signal - yes --> hit

signal - no --> miss

no signal - yes --> false alarm

no signal - no --> correct rejection

Front 13

sensitivity - % correct formula

Back 13

% correct = (% hits + % correct responses) / 2

Front 14

true or false: Hearing impaired ears have narrow auditory filters

Back 14

false

Front 15

bandwidth

Back 15

the frequency range of the auditory stimuli

Front 16

where does masking occur in the auditory system?

Back 16

energetic - peripheral auditory system

informational - CANS

Front 17

what makes one noise more disruptive than another?

Back 17

the more similar the masker and the target, the more difficult it is to separate them

Front 18

why do HoH people have difficulty understanding speech in noise?

Back 18

ex: broader auditory filters

Front 19

what can be done to reduce interference by noise?

Back 19

spatial separation of sources, visual cues, knowledge of the topic being discussed

Front 20

describe the critical band

Back 20

the critical band is the filter in which the target signal sits. anything outside of the critical band will not affect or will help our ability to hear the tone

Front 21

what two types of experiments are used to measure auditory filters?

Back 21

Psychophysical tuning curves and the notched noise method

Front 22

psychophysical tuning curve

Back 22

-threshold for fixed-frequency signal (at low level)

- masker frequency is varied

- measure level of noise needed to just detect the tone

(basically we present the target at a fixed level. frequency and intensity of the masker are varied. we vary these until we can see the threshold of the masking target)

Front 23

notched noise method

Back 23

- detect a tone in notched-noise

- vary the width of the "notch"

Front 24

explain the shape of a psychophysical tuning curve

Back 24

the curve shows the minimum the masker has to be to detect the target. Therefore, the shape is a valley. The closer in frequency the masker and target are, the less intense the masker needs to be to detect the target.

Front 25

masking

Back 25

degraded perception of a target stimulus due to the presence of irrelevant interfering speech and/or noise.

Front 26

energetic masking

Back 26

peripheral AS. when there is overlap in neural excitation between the target and interfering signals (both spectrally and temporally). failure of frequency analysis at the level of the cochlea

Front 27

informational masking

Back 27

derives in the CANS. characterized by confusability of stimuli. perceptual interference resulting from masker uncertainty or novelty

Front 28

Fletcher's Bandlimiting Experiment

Back 28

Trying to find the critical band. Started with no noise and increased the masker. The thresholds increased until the noise bandwidth exceeded the filter bandwidth --> CB!

Front 29

Swamp

Back 29

when the masker produces a significant amount of activity in the auditory filter of the target, the activity created by the target may be undetectable. Neuronal firing of the target occurs but masking is swamping it out --> "activity" occurs, but we can't detect it

Front 30

Suppressing the target

Back 30

masker suppresses the activity that the signal would evoke if presented alone. "activity" reduced for the target because it is occurring for the masker as well.

Front 31

What did Brungart, 2001 show?

Back 31

At 0 SNR, as the target and masker became more similar (different sex-->same sex-->same talker), % correct went down

Front 32

Spatial Release from Masking

Back 32

-improvement of speech intelligibility when the target is spatially separated or perceived to be separated from the interferer. Reduction in masking through spatial separation.

Front 33

how do NH and BiCI children react when the target and interferers are same-sex takers?

Back 33

SRM increases suggesting that spatial cues are more useful when spectral differences are limited

Front 34

spatially separating X is more helpful than separating Y because Z

Back 34

X = same sex

Y = different sex

Z = lac spectral difference means more benefit from spatial separation

Front 35

true or false: Executive function does not account for variability in SRM over other factors like age, expressive vocab, etc

Back 35

true

Front 36

name some objective and subjective aspects of loudness and pitch

Back 36

objective: intensity, amplitude, frequency

subjective: loudness, pitch, timbre

Front 37

How do we measure loudness?

Back 37

Magnitude estimation - present listener with reference sound and have her adjust intensity of comparison sound until the perceived loudness matches (rating on an arbitrary scale)

Magnitude production - listener adjusts level of sound until it reaches some absolute, or until it reaches a relative of the standard (ex: twice as loud)

Front 38

Helmholz theory of pitch

Back 38

Place Code theory - stimulus is analyzed by the ear, different frequencies excite different places on the BM and different AN fibers (tonotopic org of the AS), pitch is related to the pattern of excitation produced by the stimulus

Front 39

temporal theory of pitch

Back 39

pitch is related to the temporal pattern of neural impulses evoked by a stimulus

Front 40

pitch of the missing fundamental

Back 40

we can determine the pitch of a complex tone by listening only to the fundamental, even if it's not actually in the signal

Front 41

how can you measure loudness using a 2-AFC task?

Back 41

AFC = Alternative Force Choice. Play 2 tones and ask which is softer or louder

Front 42

temporal auditory processing

Back 42

rate at which auditory info is process/analyzed. perception of sound within a restricted time domain

Front 43

describe test of temporal ordering

Back 43

Ordering = processing stimuli in order of appearance. Frequency and duration. participant is asked to describe the tones in terms of pitch and length (high high low, long short long, etc)

Front 44

test of temporal resolution

Back 44

we're testing smallest interval between two tones to have them be perceived as separate. Gap Detection Test.

Front 45

stream

Back 45

when sounds are grouped together and distinct from other simultaneously occurring sequences

Front 46

which groups often have deficits in temporal processing?

Back 46

older listeners and CAPD individuals

Front 47

if we have a 4000 Hz signal, what is the ITD?

Back 47

0.25 ms

Front 48

what is the average max ITD for an adult?

Back 48

0.6 to 0.7 ms

Front 49

auditory object

Back 49

fundamental perceptual unit of hearing. putting meaning to a sound. processing and formation of them occurs in the cortex.

Front 50

objects and streams

Back 50

ex: a person walking. Each sound is an object, but over time it groups into a stream.

Front 51

name things that help us segregate streams

Back 51

intensity, timing, attention, common fate, belongingness, similarity, duration, novelty, location, visual cues, timbre, prior knowledge, patterns over time, noise or in quiet, frequency

Front 52

binaural loudness summation

Back 52

sound heard with both ears is perceived as louder than the same sound heard with one ear

Front 53

binaural squelch

Back 53

improvement resulting from adding input from ear with poorer SNR

Front 54

Duplex theory

Back 54

ITD and ILD are processed by different mechanisms in the brain. ITD --> MSO. ILD --> LSO

Front 55

Binaural release from masking

Back 55

better able to hear a signal in noise with 2 ears as long as the signal and noise are coming from different directions (this is a central phenomenon while head shadow is a monaural/peripheral thing)

Front 56

Binaural masking level difference

Back 56

S[0] - signal presented binaurally, no interaural difference

N[0] - masker ""

S[pi] = signal 180 degrees out of phase with other ear

N[pi] = masker ""

Front 57

Precedence Effect

Back 57

ability of the auditory system to make use of timing differences between the ears to suppress sounds that follow shortly after a direct sound source is emitted (localization info in the source gets precedence over reflections)

Front 58

fusion and build-up

Back 58

if the lead and the lag are close enough they fuse. if not, they don't fuse (echo threshold is when two sounds are heard) BUT over time the AS will suppress the lag (Build-up effect)

Front 59

binaural adaptation

Back 59

we become insensitive to binaural cues that are continuously repeated

Front 60

jeffress model

Back 60

1. temporally-coded input signals consisting of spikes that are time-locked to the waveform of the acoustic stimulus,
2. two sets of tapped conduction delay lines that differentially delay these monaural neural patterns that are then fed into
3. an array of binaural spike coincidence detectors, whose outputs are then inputs into
4. coincidence counters that provide the number of coincidences as a function of relative delay.

IOW: Coincidence detection in the MSO. From each side axons (delay lines) meet. Depending on where they meet on the coincidence detector cells, we can localize a sound

Front 61

Knudsen

Back 61

barn owls had prisms put over their eyes. the auditory system eventually changed to match the modified visual signal.

Front 62

King et al

Back 62

ferrets --> juveniles with one plugged ear localized pretty well. initially, a plugged adult doesn't do well; they adapt eventually.

Front 63

Sharma et al

Back 63

P1 - evoked response higher in the cortex (corresponds to speech perception). Associated with central maturation of the auditory system. The shorter the latency (the earlier CI was implanted), the more mature the auditory system. Basically, the earlier the implantation, the more normal the responses. the early implanted tend to be pretty normal while the late kids plateau

Front 64

auditory pathway parts

Back 64

outer ear/middle ear/cochlea/auditory nerve/CN (DCN/VCN [AVCN/PVCN])/MNTB/SOC (LSO/MSO)/Lateral Lemniscus/Inferior colliculus/medial geniculate nucleus/auditory cortex

Front 65

CN

Back 65

First site of parallel processing. DCN - spectral information VCN - timing

Front 66

MNTB

Back 66

Medial Nucleus of the trapezoid body. Relay station from CN to contralateral LSO - codes inhibitory information

Front 67

outer ear functions

Back 67

protect, amplify, localize

Front 68

middle ear functions

Back 68

protect, impedance matching

Front 69

inner ear functions

Back 69

filtering, transduction

Front 70

OHC does three things...?

Back 70

Amplify IHC response by moving the BM, compress - increase the range of sounds that are heard, and sharpen the IHC response