Task 8 - A scene made of sounds

Question 1

What is interaural time difference (ITD)?

Answer 1

The difference in time between when a sound reaches one ear versus the other

Question 2

How does ITD help in sound localization?

Answer 2

ITD allows us to locate sounds along the horizontal plane (azimuth) by comparing arrival times at each ear.

Question 3

What is azimuth in auditory perception?

Answer 3

The angle of a sound source on the horizontal plane relative to the center of the head.

Question 4

What brain structure first processes binaural (both-ear) sound input?

Answer 4

The medial superior olives (MSOs) in the brainstem.

Question 5

What is the Jeffress neural coincidence model?

Answer 5

A theory stating that neurons in the MSO fire the most when sound reaches both ears at a specific time difference, allowing for sound localization.

Question 6

What is interaural level difference (ILD)?

Answer 6

The difference in sound intensity between the two ears due to the head blocking sound waves.

Question 7

Which structure processes ILDs in the brain?

Answer 7

The lateral superior olives (LSOs).

Question 8

What is an acoustic shadow?

Answer 8

The reduction in sound intensity at the far ear due to the head blocking sound waves, contributing to ILDs.

Question 9

Why are ILDs more effective for high-frequency sounds?

Answer 9

High-frequency sounds are more affected by head blockage, making ILDs a stronger cue for localization.

Question 10

What is a cone of confusion?

Answer 10

A region in space where all sounds produce the same ITDs and ILDs, making localization difficult.

Question 11

How do we resolve the cone of confusion?

Answer 11

By moving our head, which changes ITDs and ILDs, allowing for accurate localization.

Question 12

What is a spectral cue for sound localization?

Answer 12

A localization cue based on how the pinna, head, and body shape affect sound frequencies.

Question 13

What is the directional transfer function (DTF)?

Answer 13

A measure of how the pinna, ear canal, head, and torso modify sound frequencies to aid in localization

Question 14

What are the two main pathways in auditory processing?

Answer 14

The “what” pathway (identifies sounds) and the “where” pathway (localizes sounds).

Question 15

What is auditory distance perception?

Answer 15

The ability to judge how far away a sound source is.

Question 16

What is the most effective cue for auditory distance perception?

Answer 16

Relative intensity – sounds become less intense with distance.

Question 17

What is spectral composition in distance perception?

Answer 17

High frequencies are dampened more than low frequencies as sound travels long distances.

Question 18

How does direct vs. reverberant energy help with distance perception?

Answer 18

Closer sounds have more direct energy, while farther sounds have more reverberant (reflected) energy.

Question 19

What is echolocation?

Answer 19

The ability to navigate or detect objects using reflected sound waves, commonly used by blind individuals and bats.

Question 20

What brain region is activated in blind individuals using echolocation?

Answer 20

The visual cortex, showing cross-modal plasticity.

Question 21

What is auditory scene analysis?

Answer 21

The process of separating and identifying different sound sources in a complex auditory environment.

Question 22

What are the three types of auditory segregation?

Answer 22

Spatial, spectral, and temporal segregation.

Question 23

What is spatial segregation?

Answer 23

Grouping sounds based on their location in space.

Question 24

What is spectral segregation?

Answer 24

Grouping sounds based on their frequency content.

Question 25

What is harmonicity in spectral segregation?

Answer 25

The tendency to group frequencies that are harmonics (integer multiples) of a fundamental frequency.

Question 26

What is the scale illusion?

Answer 26

A phenomenon where people group notes into smooth sequences when presented with alternating high and low tones in different ears.

Question 27

What is grouping by timbre?

Answer 27

Grouping sounds based on their quality, allowing us to distinguish instruments in an orchestra.

Question 28

What is grouping by onset?

Answer 28

Sounds that start at the same time are perceived as coming from the same source (common fate principle).

Question 29

How does previous experience affect auditory grouping?

Answer 29

Familiar sounds are more easily recognized and separated from other sounds.

Question 30

What is perceptual restoration?

Answer 30

The brain's ability to "fill in" missing sounds if they are masked by noise.

Question 31

How does perceptual restoration apply to speech?

Answer 31

If parts of a word are replaced by noise, listeners still perceive the full word based on context.

Question 32

What is the acoustic startle reflex?

Answer 32

A rapid, automatic response to sudden loud sounds, influenced by emotional state.

Question 33

What is inattentional deafness?

Answer 33

The failure to hear sounds due to selective auditory attention on another sound.

Question 34

Why is it harder to focus on a specific sound in a noisy environment?

Answer 34

The brain has limited attentional resources, making it difficult to filter out background noise.

Question 35

What is the role of the anterior belt area in sound perception?

Answer 35

It processes complex sounds and patterns, helping to identify "what" a sound is.

Question 36

What is the role of the posterior belt area in sound perception?

Answer 36

It processes sound localization, helping to determine "where" a sound is coming from.

Question 37

How does head movement improve sound localization?

Answer 37

Moving the head changes ITDs and ILDs, helping resolve cones of confusion.

Question 38

How does the brain combine input from both ears to form a single perception?

Answer 38

By integrating ITDs, ILDs, and spectral cues, the brain merges sound signals into one unified perception.

Question 39

Why does the pinna help with vertical localization?

Answer 39

It modifies sound frequencies differently depending on the elevation of the sound source.

Question 40

How does the shape of the head and torso influence sound localization?

Answer 40

They affect the intensity of different frequencies, creating spectral cues for localization.

Question 41

How do humans judge the distance of a sound source?

Answer 41

By using intensity, spectral composition, and the ratio of direct vs. reverberant energy.

Question 42

What is the best range for judging sound distance?

Answer 42

Humans are most accurate at estimating distances of sounds about 1 meter away.

Question 43

Why do we overestimate the distance of nearby sounds?

Answer 43

Because close sounds lose intensity rapidly, making them seem farther than they are.

Question 44

Why do we underestimate the distance of far sounds?

Answer 44

Distant sounds lose intensity gradually, making them seem closer than they actually are.

Question 45

How do blind individuals develop enhanced auditory perception?

Answer 45

They rely more on spatial hearing and can even use echolocation to navigate.

Question 46

What brain area is activated in blind individuals who echolocate?

Answer 46

The visual cortex, suggesting that it adapts to process auditory information.

Question 47

How do we separate multiple sound sources in a noisy environment?

Answer 47

Through auditory scene analysis, using spatial, spectral, and temporal cues.

Question 48

What is the cocktail party effect?

Answer 48

The ability to focus on one voice in a noisy room while filtering out other sounds.

Question 49

What is harmonicity in auditory grouping?

Answer 49

The brain groups frequencies that are integer multiples of a fundamental frequency as coming from the same source.

Question 50

What is the continuity illusion in auditory perception?

Answer 50

When a sound is interrupted by noise, the brain fills in the missing part as if it were continuous.

Question 51

What is good continuation in auditory perception?

Answer 51

Sounds following a continuous trajectory are grouped together, even when interrupted.

Question 52

How does previous knowledge influence auditory perception?

Answer 52

The brain uses past experiences to recognize and separate familiar sounds.

Question 53

What is the effect of experience on sound localization?

Answer 53

People learn how their own pinnae and head shape affect sound, improving localization over time.

Question 54

What experiment showed that humans can adapt to changes in sound localization?

Answer 54

When people wore plastic ear molds, their localization was impaired but improved over time.

Question 55

What is the scale illusion?

Answer 55

When two alternating notes are played in different ears, the brain perceives a smooth melodic sequence instead.

Question 56

What is grouping by timbre?

Answer 56

Sounds with similar timbre (tone quality) are grouped together, helping identify instruments in a song.

Question 57

What is grouping by onset?

Answer 57

Sounds that start at the same time are perceived as coming from the same source (common fate principle).

Question 58

How does the brain distinguish between different voices in a conversation?

Answer 58

By using spectral differences (pitch, timbre) and temporal differences (timing, onset cues).

Question 59

What is inattentional deafness?

Answer 59

Failing to hear sounds due to focusing attention on another auditory task.

Question 60

How does emotional state affect the acoustic startle reflex?

Answer 60

Fear or anxiety can increase the startle response to sudden sounds.