PHGY 314 Lecture Notes - Lecture 13: Cochlear Duct, Cochlea, Tectorial Membrane
31 Oct 2016
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Topics for the 4 lectures starting today: peripheral auditory system, hair cells, auditory nerves, auditory brain: sound localization, auditory brain: perception. Auditory cells and circuits are plastic during critical period, then are terminally differentiated and not replaced. So fix problems before critical period expires: hearing is critical for speech, so newborn hearing screenings (cid:1) put mic in ear, play music. Mic should pick up a sound produced by ear if it"s functional (cid:1) this is crude test, would fail if ear is still fluid-filled, which is common for babies. 40% adults over 75 = hearing impaired: loss is irreversible, incr with age. 2 properties, represented in sinusoidal wave: pitch/frequency (hz) how fast is air moving, audible range: 20-20000hz, loudness/intensity/pressure amplitude (db, dynes/cm^2, pascals) how big are the pressure changes, range 0. 0002(cid:2) 2000 dynes/cm^2. Middle ear has 2 important functions for transferring sound:
