Psychophysics: Detection

Question 1

What 5 things does a person do with a sound?

Answer 1

1.) Detection
2.) Discrimination
3.) Localization
4.) Identification
5.) Comprehension

Question 2

Who was Gustav Fechner?

Answer 2

Inventor of psychophysics in the 1800s

Question 3

What is psychophysics?

Answer 3

The mapping of a physical characteristic of a stimulus to a psychological percept

Question 4

What are the 3 elements of psychophysics?

Answer 4

1.) Method of constant stimuli
2.) Method of limits
3.) Method of adjustment

Question 5

What are the 2 problems associated with the method of limits?

Answer 5

1.) Error of habituation
2.) Error of anticipation

Question 6

What is Bekesy Tracking?

Answer 6

Von Bekesy takes the method of limits and cleans it up. Brings a person in and sits them down and starts with a loud sound and go down. As soon as the person can’t hear it, take the level up until they can hear it again, then bring it down again, then bring it up, repeat. Tracks the reversal points where the person changes their response and is closer to their threshold. Averages these reversal points.

Question 7

What was the problem with the method of limits?

Answer 7

These methods are not efficient because you spend a lot of time presenting sounds that are too loud/soft and not actually near their threshold. Wasting everyone’s time.

Question 8

What is Weber’s Law?

Answer 8

Change in a stimulus / reference stimulus = constant percentage

Question 9

What is the problem that threshold presents?

Answer 9

Should hearing always be a yes/no response 100% of the time? You either hear it or you don’t….

Question 10

What is Signal Detection Theory?

Answer 10

A framework that allows you to separate a person’s sensitivity from their response bias

Question 11

What can affect response biases?

Answer 11

Priming or external motivations

Question 12

What can affect a person’s response to not make it yes/no 100% of the time?

Answer 12

1.) Physiological noise
2.) Spontaneous firing of auditory neurons

Question 13

How does SDT measure sensitivity?

Answer 13

It is the distance between the means of the distributions (signal, signal+noise)

Question 14

In SDT, if a signal was presented and you say yes, it is a ____

Answer 14

Hit

Question 15

In SDT, if a signal was presented and you say no, it is a ___

Answer 15

Miss

Question 16

In SDT, if a signal was not presented and you say yes, it was a ___

Answer 16

False Alarm

Question 17

In SDT, if a signal was not presented and you say no, it is a ___

Answer 17

Correct Rejection

Question 18

What is D-Prime?

Answer 18

The measure of sensitivity
d’=mean(SN) - mean(N)

Question 19

How would you apply the concepts of SDT to create a test?

Answer 19

1.) Good sensitivity by having a high hit rate; it detects a disorder when it is actually present
2.) Good specificity by having a low false alarm rate; it does not detect a disorder when there is none present

Question 20

What 5 things does the smallest sound a person can hear depend on?

Answer 20

1.) How you make the measurement
2.) Duration of the sound
3.) Continuous vs intermittent sounds
4.) Frequency of sound
5.) The question you’re asking

Question 21

In what range are afferent fibers most dense?

Answer 21

1000-4000Hz

Question 22

What is afferent innervation density?

Answer 22

The place where afferent fibers are most dense and multivesicular. The 1000-4000Hz range

Question 23

Why are intermittent sounds better than continuous sounds?

Answer 23

If an intermittent tone is presented, it has a lot of onset and gives more detectable cues (onset bursts) to the person and better detection of a sound.

Question 24

What is temporal summation?

Answer 24

The perceived loudness of a sound increases as its duration lengthens, meaning the longer a sound lasts, the louder it seems, especially when the sound is short in duration
Essentially, the ear integrates the sound energy over time, leading to a stronger neural response with longer stimulus presentation

Question 25

Does Weber’s Law hold for frequency?

Answer 25

Yes, it kind of works between 500Hz and 2000Hz. Outside of that range, no

Question 26

Does Weber’s Law hold for intensity?

Answer 26

“Near miss”; It is a slightly downturned line, not a straight horizontal line

Question 27

Does Weber’s Law work for duration?

Answer 27

No because the graph uses a log scale

Question 28

Why is the gap discrimination task problematic?

Answer 28

People are making a discrimination based on the absence of sound rather than the actual sound

Question 29

When presented with 2 sounds of equal loudness, why might a person decide the two sounds are different?

Answer 29

A person might decide a second sound is different than another because it might seem louder because it has more total energy, not duration at all. Using the wrong basis.

Question 30

What is the percept of frequency?

Answer 30

Pitch

Question 31

What is the percept of intensity?

Answer 31

Loudness

Question 32

What is the percept of harmonics?

Answer 32

Timbre

Question 33

What is the percept of phase?

Answer 33

Location

Question 34

Why is the dynamic range of hearing different at 1000Hz than 100Hz?

Answer 34

Detection of sound is different for different frequencies. You need a higher intensity to hear something at 1000Hz than 100Hz. There is a difference between threshold levels and discomfort levels when processing loudness.