buy Viagra 200 mg in Ann Arbor Michigan During year 8 pupils will study the Sound and hearing unit. In this unit they need to know the structure and function of the ear. I have attached a diagram of the ear below so that you can see the structure.
http://seaprof.com/courses/calendar/action~oneday/page_offset~-2/time_limit~1416067200/cat_ids~5/request_format~html/ The image of the ear is supplied by Alila Medical media to see more images of the ear and hearing click on the link.
As the sound wave enters the ear, it will cause the ear drum to vibrate. The will cause the three bones (ossicles) to move. The three bones are the hammer, anvil and stirrup. As the stirrup bone moves backwards and forwards it causes the thin membrane covering the oval window to move. The movement of the oval window membrane causes waves to be created that travel through the cochlear fluid. As the cochlea fluid moves it will cause nerve impulses to be sent to the brain.
Humans have an audible hearing range of 20Hz to 20,000Hz. As we get older the hearing range tends to decrease so we can’t hear dull or high pitched sounds.
If the sound becomes louder, then the ear drum vibrates further. If the sound has a higher pitch then the ear drum vibrates faster.