Chapter 12-Sound localization and Organization Flashcards
Define auditory space
We perceive objects and events to happen in positions depending solely on sound- very similar to how we perceive visual space
Define auditory localization
We can localize an objects position in space based on sound
What are the three dimensions used to identify sound localization?
Azimuth
Elevation
Distance
Define Azimuth
The horizontal meridian that is measured in degrees to assist in finding the distance between the listener and object
is used when turning your head- side to side motion
Define Elevation
The vertical meridian measured in degrees to assist in finding the distance between the listener and the object
is used by moving head up and down-> nodding
Distance
the difference in space between the listener and object
When is the azimuth and elevation equal to 0 degrees?
When the viewer is looking straight ahead
Where are humans best at localizing sound?
When the sound is directly in front of them
What is the primary receptor of sound?
The cochlea
What is the role of the cochlea?
to detect sound frequencies
What does the auditory system use to localize sound?
Location cues
What are location cues?
The auditory version of depth cues
are both binaural and monaural cues
What do Binaural cues detect?
Interaural time difference and interaural level differences
What do monaural cues detect?
Head and pinnae shape
What does ITD stand for?
Interaural Time Difference?
What is the interaural time difference when sound approaches from straight ahead of a person?
Because the sound will arrive at each ear at the same time the ITD will be 0
What is the interaural time difference when sound approaches from one side of a person?
Because it will take the sound longer to reach one ear than the other the ITD will be greater than 0
What is ITD referred to when there are continuous sounds?
Interaural phase difference
Why can we only detect phase differences in long wavelengths (lower frequencies) and not shorter wavelengths (higher pitch)
The wavelengths must be long enough to reach both ears
What does ILD stand for?
Interaural Level Difference
Define an acoustic shadow
the barrier our heads create to reduce the intensity of sounds reaching our far ear
When does the acoustic shadow not work?
When the soundwave is wider than the head- aprox. 1000-2000 hz
Which dimension relies on ITD and ILD
Azimuth
Which frequencies does ITD rely on
low frequencies between 20-1000Hz
Which binaural cue dominates?
Interaural time difference
Which binaural cue dominates?
Interaural time difference
Why is ITD used more than ILD
ITD is used more frequently because most sounds occur between 20 and 1000hz
Are binaural cues useful for elevation?
no
Why do we only need on pinae to make sense of monaural cues?
We only need one pinae to make sense of monaural cues because constructive and destructive interference aid us in finding the elevation of sound
Which is associated with elevation; monaural or binaural cues?
Monaural cues are associated with elevation
Interaction with what body parts change the characteristics of sound?
Head and pinae
what is constructive and destructive interference dependent on?
the incoming angle of the soundwave relative to the head and pinnae
why is it called the spectral cue
Depending on the position of the soundwave entering the ear the frequency will increase or decrease–> therefore the frequency lands on a spectrum
Does the spectral cue affect the azimuth or the elevation?
elevation
Who has broader ITD neurons? Barn owls, or gerbils?
Gerbils
What is the order of structures in the central auditory processing system
Cochlear nucleus
Superior olivary nucleus
Inferior colliculus
Medial geniculate nucleus
What is an acronym for the central auditory processing system?
COCK SONIC MG–> a very fast car
Where does binaural processing start?
Superior olivary nucleus
Breakdown the acronym for the structures in the central auditory processing system
COCK–> Cochlear nucleus
SON–> Superior olivary nucleus
IC–> Inferior colliculus
MG–> Medial geniculate nucleus
Identify where the ventral stream for the auditory system is in the brain
located in the anterior portion of the belt threads through the temporal and prefrontal cortex
What is the function of the ventral stream in the auditory system
The ‘what’ stream
identifies sound
Identify where the dorsal stream for the auditory system is in the brain
Originates at the posterior belt and is strung to the parietal and prefrontal cortices
What is the function of the dorsal stream in the auditory system?
The where–> therefore finding where sound is coming from
Describe cryoloop activation
Cooling areas of the brain to cause temporary inactivation- acts as a temporary lesion
What is a key difference in the visual and auditory systems receptive fields?
Receptive field location is DIRECTED in vision, whereas in hearing the receptive field location is calculated.
Define direct sounds
Sound waves directly coming from the source to your ear- more likely to experience indoors
Define indirect sounds
Sound Waves bouncing off objects between the source and your ear- more likely to experience outside
What is the precedence effect?
Our ability to locate sounds is not affected by indirect sounds. However, indirect sounds will affect our perception of sound quality
Define echo threshold
When there is a delay between direct and indirect sound we will hear an echo
What affects echo threshold?
when lag sound is quieter than the lead sound and sounds with longer durations such as speech and music
What is our perception of sound based on?
sound produced at the source
How sounds are reflected before they reach our ears
What field is concerned with the study of how sounds are reflected in rooms and the practical application for auditory psychophysics?
Architectural acoustics
What do acoustic engineers do?
design concert halls that have favorable acoustical properties compared to a subset of subjective prototypes
What effect does absorption have on sound waves?
Lots of absorption=few reflected soundwaves and little indirect sound
Little absorption=MANY reflected sound waves and lots of indirect sound
What effect does the design of the room have on soundwaves?
Room size affects the time it takes indirect sounds to reach the listener
Room shape affects the direction reflected sound waves will be sent
