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Unformatted text preview: What and how we hear Visual n hearing system – very similar- suggests organization follows same scheme- some variations here and there – sound and light wave 1. what’s sound 2. how is sound amplified by outer and middle ear- rods n cons (ojo)- hair cells (oreja) 3. how do hair cells transduce sound into action potentials in action potential- optic nerves cross n make first synapse in the genicular thalamus 4. what’s the pathway to cortex- Light – photoreceptors on retina (rods and cones) – 1 st synapse at bipolar cells – 2 nd synapse at ganglion cells – axons of ganglion cells make optic nerve – axons extend to lateral genicular nucleus of thalamus – primary visual cortex in occipital lobe of cortex – secondary visual cortex – synapse ? with association cells- Sound – outer ear – ear canal – eardrum – malleus, incus, stapes – cochlea – cilia attached to hair cells – axons of hair cells make up auditory nerve – 1st synapse at superior olivary nucleus – 2 nd synapse at inferior colliculi – 3 rd synapse at medial geniculate nucleus of thalamus – final synapse at primary auditory cortex 5. how does the brain code for pitch (frequency) and for location of sound- what n where 6. is coding influenced by early experience- humans move head, not ear unlike some animals- language is both heard n perceived- sound is not just absorbed, it’s analyzed/interpretated by brain () 1. Sound- pressure in the air- physical dimension/perceptual dimension: o amplitude (intensity)/loudness; o frequency/pitch; o complexity/timbre [pic] Division of ear- Outer ear : channel to tympanic membrane o Ear canal filled with wax o Has membrane – ear drum- Middle ear : ossicles o 3 bones (malleus, incus, stapes) o Motor nerve, cranial verb o Muscle can hold onto incus, stiffen it to dampen loud sound- Inner ear : cochlea o Oval window o Sound waves get moved to waves of liquid o Fluid filled o Fluid moves through cochlea o Chochlea has receptos for sound called hair cells o Tip has cilia that waves Audition Anatomy • air pressure waves enter the auditory canal, and impinge upon tympanic membrane drum)...
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- Fall '08
- hair cell, hair cells