Chapter 12

Question 1

what is auditory space?

Answer 1

Sounds at different locations that exist all around. This creates an auditory space

Question 2

What is auditory localization?

Answer 2

The locating of sound sources in auditory space

Question 3

What are location cues?

Answer 3

In hearing, characteristics of the sound reaching the listener that provide information regarding the location of a sound source.

It is created by the way sound interacts with the listener’s head and ears.

Question 4

Explain the two types of location ques: binaural cues and spectral cues

Answer 4

binaural cues: depend on both ears

spectral cues: depend on just one ear

Question 5

Explain how people can utilize these cues to locate the position of a sound in three dimensions.
1. azimuth
2. elevation
3. distance

Answer 5

1. azimuth: In hearing, specifies locations that vary from left to right relative to the listener.
2. elevation: In hearing, sound locations that are up and down relative to the listener.
3. distance: How far a stimulus is from the observer. In hearing, the distance coordinate specifies how far the sound source is from the listener.

Question 6

Binaural cues use information reaching both ears to determine the azimuth (left–right position) of sound.

Explain the two types of binaural cues:
interaural level difference and interaural time difference.

Answer 6

interaural level difference:
The difference in the sound pressure (or level) between the left and right ears. This difference creates an acoustic shadow for the far ear. The ILD provides a cue for sound localization for high-frequency sounds.
To sum: one ear hears it more - and one ear is blocked by head to hear less

interaural time difference:
When a sound is positioned closer to one ear than to the other, the sound reaches the close ear slightly before reaching the far ear, so there is a difference in the time of arrival at the two ears. The ITD provides a cue for sound localization.
To sum: one ear gets hit first

Question 7

What is the cone of confusion?

Answer 7

All points on the surface of this cone have the same ILD and ITD.
only difference is elevation, which can confuse us.

Question 8

What are spectral cues?

Answer 8

Elevation cues.
In hearing, the distribution of frequencies reaching the ear that are associated with specific locations of a sound. The differences in frequencies are caused by interaction of sound with the listener’s head and pinnae.

To sum: sound hits pinna differently when elevation is different

Question 9

What does the Jeffress model of auditory localization propose?

Answer 9

neurons are wired so they each receive signals from the two ears

Neurons fire in each ear and meet at a spot. If left gets it faster, it goes further. So the meeting spot will be more then halfway. This could help us indicate timing. (I’m describing the picture)

Question 10

What are coincidence detectors in the Jeffress model of auditory localization?

Answer 10

Neurons in the Jeffress neural coincidence model,

which was proposed to explain how neural firing can provide information regarding the location of a sound source. A neural coincidence detector fires when signals from the left and right ears reach the neuron simultaneously. Different neural coincidence detectors fire to different values of interaural time difference.

Question 11

What is ITD tuning curves (interaural time difference)?

Answer 11

A way to test the ITD neurons
which plots the neuron’s firing rate against the ITD (interaural time difference).

Question 12

What are ITD detectors in the Jeffress neural coincidence model ?

Answer 12

Interaural time difference detector. Neurons in the Jeffress neural coincidence model that fire when signals reach them from the left and right ears. Each ITD detector is tuned to respond to a specific time delay between the two signals, and so provides information about possible locations of a sound source.

Question 13

What is an intact auditory cortex necessary for?

Answer 13

accurate localization of sounds in space.

Used cats, taught them localization then lesioned this area.

Question 14

What does lesioning the primary auditory cortex cause?

Answer 14

decreased, but did not totally eliminate, the ferrets’ ability to localize sounds.

Question 15

What does the anterior belt area do?

And what pathway does it start?

Answer 15

The front of the posterior belt in the temporal lobe, which is involved in perceiving sound.

perceiving complex sounds and patterns of sound

what auditory pathway, which extends from the anterior belt to the front of the temporal lobe and then to the frontal cortex

Question 16

What does the posterior belt area do?

Answer 16

Posterior (toward the back of the brain) area of the belt area, which is an area in the temporal lobe involved in auditory processing.

involved in localizing sounds

where auditory pathway, which extends from the posterior belt to the parietal lobe and then to the frontal cortex

Question 17

What is indirect sound?

Answer 17

which reaches your ears after bouncing off the auditorium’s walls, ceiling, floor, etc

Question 17

Explain lead speaker and second speaker delay phenomenon?

Answer 17

If a sound is presented in the lead speaker followed by a long delay (tenths of a second), and then a sound is presented in the lag speaker, listeners typically hear two separate sounds—one from the left (lead) followed by one from the right (lag) (Figure 12.14a). But when the delay between the lead and lag sounds is much shorter, as often occurs in a room, something different happens. Even though the sound is coming from both speakers, listeners hear a single sound as coming only from the lead speaker

Question 17

What is direct sound

Answer 17

sound that reaches your ears directly

Question 18

What is the precedence effect?

Answer 18

When two identical or very similar sounds reach a listener’s ears separated by a time interval of less than about 50 to 100 ms, the listener hears the first sound that reaches his or her ears.

Question 19

What are Architectural acoustics?

Answer 19

The study of how sounds are reflected in rooms. An important concern of architectural acoustics is how these reflected sounds change the quality of the sounds we hear.
Shape of room influences this.

Question 19

What is reverberation time?

Answer 19

The time it takes for a sound produced in an enclosed space to decrease to 1/1,000th of its original pressure.

Question 20

What happens when reverberation time is too long?

Answer 20

If the reverberation time of a room is too long, sounds become muddled because the reflected sounds persist for too long. In extreme cases, such as cathedrals with stone walls, these delays are perceived as echoes,

Question 21

What happens when reverberation time is too short?

Answer 21

If the reverberation time is too short, music sounds “dead,” and it becomes more difficult to produce high-intensity sounds

Question 22

Explain the following physical measures are associated with how music is perceived in concert halls:
1. Intimacy time
2. Bass ratio
3. Spaciousness factor

Answer 22

1. Intimacy time:
   The time between when sound arrives directly from the stage and when the first reflection arrives. This is related to reverberation but involves just comparing the time between the direct sound and the first reflection, rather than the time it takes for many reflections to die down.
2. Bass ratio:
   The ratio of low frequencies to middle frequencies that are reflected from walls and other surfaces
3. Spaciousness factor:
   The fraction of all of the sound received by a listener that is indirect sound.

Question 23

What is the auditory scene?

Answer 23

The sound environment, which includes the locations and qualities of individual sound sources.

Question 24

What is auditory scene analysis?

Answer 24

The process by which the sound stimuli produced by different sources in an auditory scene become perceptually organized into sounds at different locations and into separated streams of sound.

Question 24

Why is auditory scene analysis difficult?

Answer 24

Each musician produces a sound stimulus, but these signals are combined into one signal, which enters the ear.

Question 24

Explain the two ways we group the auditory scene into different sources:
1. simultaneous grouping
2. sequential grouping

Answer 24

1. simultaneous grouping
   The situation that occurs when sounds are perceptually grouped together because they occur simultaneously in time.
2. sequential grouping
   In auditory scene analysis, grouping that occurs as sounds follow one another in time.
   ex. Hearing the melody being played by the keyboard as a sequence of notes that are grouped together

Question 25

Explain Simultaneous Grouping
-Location
-Onset time
-Timbre and pitch
-Harmonicity

Answer 25

-Location:
Different places are often different sounds and things that move usually follow a continuous path
-Onset time:
Sounds that start at diff times are usually different
-Timbre and pitch:
similar sounds are grouped
-Harmonicity:
when we hear a harmonic series we infer that it came from a single source

Question 26

Explain Sequential Grouping:
-Similarity of Pitch (auditory stream segregation)

• Auditory Continuity

-Experience (melody schema)

Answer 26

-Similarity of Pitch (auditory stream segregation)
The perception of a string of sounds as belonging together

• Auditory Continuity: Sounds that stay constant or that change smoothly are often produced by the same source

-Experience (melody schema): The effect of past experience on the perceptual grouping of auditory stimuli can be demonstrated by presenting the melody of a familiar song

Question 27

What is the scale illusion, or melodic channeling?

Answer 27

two sequences of notes simultaneously through earphones, one to the right ear and one to the left. Notice that the notes presented to each ear jump up and down and do not create a scale. However, Deutsch’s listeners perceived smooth sequences of notes in each ear, with the higher notes in the right ear and the lower ones in the left ear. Even though each ear received both high and low notes, grouping by similarity of pitch caused listeners to group the higher notes in the right ear (which started with a high note) and the lower notes in the left ear (which started with a low note).

Question 28

What are multisensory interactions?

Answer 28

Use of a combination of senses. An example for vision and hearing is seeing a person’s lips move while listening to the person speak.

Question 29

what is ventriloquism effect, or visual capture?

Answer 29

example of vision dominating hearing. It occurs when sounds coming from one place (the ventriloquist’s mouth) appear to come from another place (the dummy’s mouth). Movement of the dummy’s mouth “captures” the sound

Question 30

What is the two-flash illusion?

Answer 30

An illusion that occurs when one flash of light is presented, accompanied by two rapidly presented tones. Presentation of the two tones causes the observer to perceive two flashes of light.

Question 31

What is speechreading?

Answer 31

Process by which deaf people determine what people are saying by observing their lip and facial movements.

Question 32

Explain the interconnection of the different sensory areas of the brain.

Monkey and parietal lobe interactions

Answer 32

Receptive fields of neurons in the monkey’s parietal lobe that respond to (a) auditory stimuli that are located in the lower left area of space and (b) visual stimuli presented in the lower left area of the monkey’s visual field. (c) Superimposing the two receptive fields indicates that there is a high level of overlap between the auditory and visual fields.

Question 33

Explain Echolocation in Blind People:

Answer 33

Daniel Kish, who has been blind since he was 13-months-old, finds his way around by clicking his tongue and listening to the echoes that bounce off of nearby objects.

is that learning to echolocate causes reorganization of the brain, and the visual area is involved because it normally contains a “retinotopic map”
The maps for echolocation in the echolocator’s visual cortex are therefore similar to the maps of visual locations in sighted people’s visual cortex.

So therefore: when sound is used to achieve spatial awareness, the visual cortex becomes involved.

Question 34

How does Listening to or Reading a Story impact what part of the brain is used?
(Hint: Visual vs auditory receiving area)

Answer 34

they found that listening to the story activated the auditory receiving area in the temporal lobe and that reading the written version activated the visual receiving area in the occipital lobe