NATS 1720 Lecture Notes - Lecture 5: Basilar Membrane, Oval Window, Cochlea

• School: York University
• Department: Natural Science
• Course: NATS 1720
• Professor: Carl Wolfe

Document Summary

Speed of wave = wavelength period ( ) = wavelength x frequency. So wavelength = speed frequency = 343 m/s 20 hz = 17. 15 m. Perception of sound: pressure wave reaches tympanic membrane ( ), which moves back and forth in response. Three small bones (ossicles ) are made to vibrate by the eardrum ( ) (amplify force 20x: ossicles press against a membrane (oval window) on the cochlea ( ). Vibration of oval window sets up pressure wave in cochlea fluid: if we unfold the cochlea, it will shapes like a tube with a membrane called basilar membrane ( . Basilar membrane (hosts organ of corti: organ of corti hosts specialized nerve cells that emit electrical signals in response to movement (hair cells ). Fech(cid:374)e(cid:396)"s la(cid:449): cha(cid:374)ges of sti(cid:373)ulus that a(cid:396)e i(cid:374) sa(cid:373)e p(cid:396)opo(cid:396)tio(cid:374) cause e(cid:395)ual cha(cid:374)ges i(cid:374) se(cid:374)satio(cid:374). 10 mpa -> 100 mpa (cid:862)s(cid:373)all(cid:863) cha(cid:374)ges i(cid:374) a(cid:373)plitude a(cid:396)e (cid:374)ot pe(cid:396)cei(cid:448)ed. Usually need a 50% increase just to notice.