Sound

1. Sound How You Hear Sound

2. How Does It Work??? • You are sound asleep. Suddenly, your alarm goes off and you jump awake. • How does your brain receive this information?

3. Function • Gather sound waves & send information about sound to your brain • Three main sections all with different functions • Outer Ear • Middle Ear • Inner Ear

4. Outer Ear • Part you see • Acts like a funnel • Collects sound waves & directs them into narrow region called ear canal • Few cm long • Ends at eardrum • Eardrum – small, tightly stretched, drumlike membrane • Sound waves make eardrum vibrate

5. Middle Ear • Behind eardrum • Contains 3 smallest bones in body • Hammer, anvil, stirrup • Hammer attached to eardrum • When eardrum vibrates, hammer does too • Transmits vibrations first to anvil then stirrup

6. Inner Ear • Membrane separates middle ear from inner ear • When stirrup vibrates against membrane, vibrations pass into cochlea – fluid filled cavity shaped like a snail shell • Contains more than 10,000 tiny hair cells

7. Inner Ear Cont. • Hair like projections float in fluid in cochlea • When vibrations move through fluid, hair cells move, causing messages to be sent to the brain through the auditory nerve • Brain then processes messages and tells you what you heard

8. - How You Hear Sound

9. Hearing Loss • If loss of hearing occurs may have difficult time hearing soft sounds or high-pitched sounds • Can be caused by • Injury • Infection • Exposure to loud sounds • aging

10. Causes of Hearing Loss • Can occur if eardrum damaged or punctured • Infections can damage inner ear • Excessive loud music can damage hair cells so can no longer send signals to brain • As age, some hair cells die in cochlea and never replaced