Final: Chapter 12 Flashcards
the ability to tell the direction from which a sound is originating.
Sound localization
a psychoacoustic phenomenon that describes how the brain perceives sound when multiple sounds reach the ear close together in time
Precedence effect
The ability to separate each of the sound sources and separate them in space is achieved
Auditory stream analysis
the process of determining which regions and parts of the visual scene belong together as parts of higher order perceptual units such as objects or patterns
Perceptual grouping
the way that auditory events are localized, or how a person perceives an auditory scene in space
Auditory space
locating of sound sources in the auditory space
Auditory localization
What is the activation of nerve fibers in the cochlea based on?
on the tones’ frequency components and not on where the tones are coming from
TRUE OR FALSE: 2 tones with the same frequency that originate in the different locations will NOT activate the same hair cells and nerve fibers in the cochlea.
FALSE, they will activate the same hair cells and nerve fibers
are created by the way sound interacts with the listener’s head and ears
Location cues
What are the 2 kinds of location cues?
Binaural and spectral cues
Location cue that depends on both ears
Binaural cues
Location cue that depends on one ear
Spectral cues
extending from left to right
Azimuth
extending up and down
Elevation
What three dimensions to locate the position of a sound are location cues used for?
- azimuth
- elevation
- distance of sound source from the listener
Based on the difference in the sound pressure level of the sound reaching the two ears
Interaural Level Difference (ILD)
reduces the intensity of sounds that reach the far ear
Acoustic shadow
What type of sound does Interaural Level Difference work best at?
high frequency sounds
The time difference between when a sound reaches the left ear and when it reaches the right ear.
Interaural Time Difference (ITD)
If the sound source is directly in front of the listener, what is the ITD? why?
The ITD is 0 because the distance to each ear is the same: the sound reaches the left and right ears simultaneously
When does ITD become larger?
When sound sources are located more to the side
ITD is most effective for determining the locations of what kind of sounds?
low frequency sounds
Cues in which information for localization is contained in differences in the distribution (or spectrum) of frequencies that reach each ear from difference locations
Spectral cues
ILDs and ITDs work for judging _________ location.
azimuth
What do spectral cues work best for?
judging elevation, especially for spectra extending to higher frequencies
Proposes that neurons are wired so they each receive signals from the two ears/ proposes a circuit that contains a series of ITD detectors, each tuned to respond best to a specific ITD
Jeffress Model of auditory localization
They only fire when both signals coincide by arriving at the neuron simultaneously/ each one fires best to a particular ITD
Coincidence detectors/ ITD dectectors
ITD is indicated by the place (which neuron) where the activity occurs
place code
Plots the neuron’s firing rate against the ITD
ITD tuning curves
What does the broadness of the ITD curves in mammals mean?
that coding for localization is based on broadly tuned neurons
What is binaural localization based on for birds?
sharply tuned neurons
What is binaural localization based on for mammals?
broadly tuned neurons
Why is the code for birds a place code?
Because ITD is indicated by the firing of neurons at a specific place in the nervous system
Why is the code for mammals a population code?
Because the ITD is determined by the firing of many broadly tuned neurons working together
What was the study done by Dewey Neff?
He placed cats about 8 feet away from 2 food boxes - one about 3 feet to the left and one about 3 feet to the right. The cats were rewarded with food if they approached the sound of a buzzer located behind one of the boxes
What did Dewey Neff conclude?
That an intact auditory cortex is necessary for accurate localization of sounds in space.
What are the 2 pathways that lead away from A1 (primary auditory cortex?
The what and where auditory pathways
Involved in perceiving complex sounds and patterns of sound
anterior belt
Involved in localizing sound
posterior belt
Extends from the anterior belt to the front of the temporal lobe and then to the frontal cortex
“what” auditory pathway
Extends from the posterior belt to the parietal lobe and then to the frontal cortex
“where” auditory pathway
associated with perceiving sounds
“what” pathway
associated with locating sounds
“where” pathway
sound that reaches your ear directly
Direct sound
When in an auditorium, what is your perception based on?
direct sound plus indirect sound
Sound that reaches your ears after bouncing off the auditorium’s walls, ceiling, and floor
Indirect sound
We perceive the sound as coming from near the source that reaches our ears first
Precedence effect
What is the point of the precedence effect?
that a sound source and its lagging reflections are perceived as a single fused sound
________ sound can affect the quality of the sound we hear
indirect
The study of how sounds are reflected in rooms that is largely concerned with how indirect sound changes the quality of the sounds we hear in rooms
Architectural acoustics
What affects indirect sounds?
- The size of the room
- The amount of sound absorbed by the walls, ceilings, and floor.
- The shape of the room
The time it takes for the sound to decrease to 1/1000th of its original pressure
reverberation time
What are the factors in designing concert halls for how music is perceived?
- reverberation time
- Intimacy time
- Bass ratio
- Spaciousness factor
The time between when sounds 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
Intimacy time
The ratio of low frequencies to middle frequencies that are reflected from walls and other surfaces
Bass ratio
The fraction of all the sound received by a listener that is indirect sound
Spaciousness factor
How long are intimacy times?
20 msec
What are high bass ratios and spaciousness factors associated with?
Good acoustics
What is one problem that occurs in concert halls?
The acoustics depend on the number of people attending a performance, because peoples’ bodies absorb sound
How do architects deal with the problem of the number of people attending changing the acoustics in concert halls?
The seat cushions were designed to have the same absorption properties as an “average” person
The process by which the stimuli produced by each source are separated
Auditory scene analysis
The array of sound sources at different locations in the environment
Auditory scene
Involves grouping the components present at a given moment in time to create one or more perceived sounds
Simultaneous grouping
Involves connecting components over time to form streams/ grouping that occurs as sounds follow one another in time.
Sequential grouping
What is one way to analyze an auditory scene into its separate components?
to use info about where each source is located
TRUE OR FALSE: If two sounds start at slightly different times, it is likely that they came from the same sources.
FALSE, likely that they came from different sources
Measures the time between the start of one stimulus and the start of another.
onset synchrony
TRUE OR FALSE: Sounds that have the same timbre or pitch range are often produced by the same source
TRUE
When we hear a harmonic series we infer that it came from a single source
Harmonicity
What helps us differentiate between the sounds of a flute and trombone as separate sources?
differences in pitch
The perception of a string of sounds as belonging together
Auditory stream segregation
produced by simultaneous ascending and descending major scales beginning in separate stereo channels with each successive note being switched to the opposite channel
Scale illusion/ melodic channeling
What did Deutsch conclude?
It is similar to the Gestalt principle of good continuity of vision; sound stimuli with the same frequency or smoothly changing frequencies are perceived as continuous even when they are interrupted by another stimulus
What study did Richard Warren demonstrate?
Auditory continuity by presenting bursts of tone interrupted by gaps of silence. But when Warren filled in the gaps with noise, listeners perceived the tone as continuing behind the noise.
A representation of a familiar melody that is stored in a person’s memory
melody schema
An 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). The movement of the dummy’s mouth “captures” the sound.
Ventriloquism effect
When a single dot is flashed onto a screen, the participant perceives one flash. When a single beep is presented at the same time as the dot, the participant still perceives one flash. However, if the single dot is accompanied by two beeps, the participant sees two flashes, even though the dot was flashed only once.
Two-flash illusion
Enables deaf people to determine what people are saying by watching their lip and facial movements.
Speechreading
What do the multisensory neurons that fire to both sound and vision help us form?
a single representation of space that involves both auditory and visual stimuli
What technique do some blind people use to locate objects and perceive shapes in the environment?
Echolocation
What part of the brain does listening to a story activate?
the auditory receiving area in the temporal lobe
What part of the brain does reading a written version of a story activate?
the visual receiving area in the occipital lobe
In what brain region are the responses from listening and from reading synchronized in time?
The superior temporal gyrus in the temporal lobe
