PHGY 314 Lecture Notes - Lecture 15: Arnold Tongue, Basilar Membrane, Sound
31 Oct 2016
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Document Summary
Ohc / ihc innervation: ~30k cochlea afferents in each ear. Efferents: olivocochlear neurons in medial olivocochlear complex (moc) in the superior olivary. Complex (soc), via cn viii (cid:1) ihc, ohc. Afferents: ihc, ohc (cid:1) spiral ganglion cells via the auditory nerve, cn viii (cid:1) cochlear nucleus: type i, type ii: Firing rate of afferents proportional to hair cell depolarization, which is proportional to sound lvl. Type i of cn viii) adapt to louder sustained sounds (ex. tone bursts) Adaptation is effected by efferent (descending control) olivocochlear neurons (from soc). Aff neuron responds less to db corresponding to noise, More to loud db corresponding to relevant noise. Duplex theory of pitch + loudness discrimination: high frequency sound: tonotopy/place code. Which nerve fiber is activated: ~10 afferents per ihc, each fires differently for the ihc"s characteristic frequency (so they vary in sensitivity, high spontaneous rate vs low spontaneous rate (sr) afferents.
