ultrasound animals
- bats
- dolphins
infrasound animals
crocodiles
blue wales
elephants
things that generate infrasound
- volcanoes
- thunderstorms
infrasound
low frequency
travel better in water
ultrasound
high frequency travels better in air
how a barrier affects waves when wavelength < barrier width
sound shadow
- sound reflected
how barrier affects waves when wavelength > barrier
wave diffracts around barrier
no effects on sound
bats and echolocation
- have to use high frequency (short wavelength) ultrasound to detect pray
- high frequency causes reflection on prey (barrier)
~ 100kHz - tells direction and location
human echolocation
- uses visual cortex (not auditory)
- blind people cannot generate 3D map of world based on visual input but can use auditory input to generate 3D ‘sound map’
what part of the brain stem helps to generate the 3D map of sound
inferior colliculus
Auditory cortex A1
- consists of tonotopic frequency representation of sound
- perception of sound
core of auditory cortex
primary auditory cortex
regions surrounding primary auditory cortex
‘belt’
- secondary auditory cortex
where do medial geniculate axons enter A1
via layer IV (4)
what is the tertiary auditory cortex
parabelt, at bottom of secondary auditory cortex
belt processing
turns separate frequencies of sound from core into words
- ‘s’ ‘a’ ‘n’ ‘d’ -> ‘sand’
auditory streams - where
postero-dorsal pathway
- parietal lobe
auditory streams - what
antero-ventral pathway
- temporal lobe
inferior temporal lobe
visual pathway
superior temporal lobe
auditory pathway
route of what pathway after temporal lobe
ventro lateral pre frontal cortex
route of where pathway after parietal lobe
dorsal lateral pre frontal cortex
damage to core of A1
cortical deafness
- can’t hear anything above 5,000Hz
damage to belt region of A1
- causes agnosia deafness
- can hear sounds but can’t recognize it
