II.1 Physical Reality II.1.2 (F Sept 15) Hearing with Ear and Brain

malleus incus stapes semicircular channels cochlea ear drum auricle 20-fold reinforcement enters the upper (oval) window of cochlea 2.5 windings 30 mm length 1 cm2

24‘000 hair cells oval window Corti organ tectorial membrane 1 mm scala media tympani vestibuli auditory nerve Reissner‘s membrane perilymph liquid endolymph liquid inner hair cells outer hair cells basilar membrane 10-8 cm in 1/200 sec 24‘000 hair cells 30-50 stereo- and 1 kino-ciliae

George von Békésy 1961, Harvard U, Nobel prize high frequencies low frequencies helicotrema stapes round window

4 major transformations of data! colliculus inferior nucleus cochlearis gyri Heschl corpus geniculatum mediale 30‘000 nerve „cables“ nuclei superiores olivae nervus cochlearis

cat brain multiple representation of same pitch low pitch cochlea high pitch