1. Senses- Ears
Hearing and balance are the main functions of hearing. Hearing works with the other 4 senses to aid us in obtaining information and keeping our bodies upright.

2. I. Functions of the Ear
Hearing
Balance

4. II. Parts of the Ear 1. Outer Ear
Pinna- fleshy curved part that is attached to each side of the head. It collects sound waves and directs them into the ear.
External Auditory Canal- a passageway about 1in. Long. Is lined with fine hairs and wax producing glands.
Tympanic Membrane (eardrum)- a thin sheet of tissue about ¼ inch across. Separates the outer ear from the middle ear

5. Parts of the Ear 2. Middle Ear
- Ossicles- 3 small bones that are linked together and connect from the eardrum to the inner ear.
1. Malleus- Hammer bone is the first and largest of the 3 ossicles.
2. Incus- Anvil bone is the middle bone
3. Stapes- Stirrup bone is the last and smallest of the 3 ossicles. Also, connects the middle ear to the inner ear.

6. Parts of the Ear 2. Middle Ear cont.
Mastoid process- small air-filled spaces in the bones that lie behind the middle ear.
Eustachian Tube- 1.5 inch long tube that connects the ear to the throat Equalizes pressure on either side of the ear.

7. Parts of the Ear 3. Inner Ear
Oval Window- where stapes connects to the vestibule.
Vestibule- (snail head) tiny baglike structures lined with hairs (balance).
Semicircular Canals- 3 canals set at right angles to one another that control your balance.

8. Inner Ear Continued
Cochlea- (snail shell) 3 fluid filled tubes that contain thousands of tiny hair cells. Organ of Corti located inside. Auditory Nerve- nerves attached to hairs in cochlea that convert sound waves to brain for processing. Round Window- expands as oval window is pushed in from vibrations.

9. The Hearing Process Vibrations in the air cause sound waves
Sound waves are collected by the pinna
Continue through external auditory canal
Eardrum vibrates
Malleus, Incus, Stapes vibrate
Oval window moves in and out with the vibrations
Vibrations travel into cochlea where hairs are stimulated
Hairs trigger nerve impulses to auditory nerve
Auditory nerve send impulses to brain for processing

10. Balance Semicircular canals are responsible for balance
Fluid in the crista of the semicircular canals move hairs when body is moved
When body moves, hairs bend and send impulses to brain.
Brain sends impulses to muscles to compensate for movement

11. Prolonged exposure to loud noise can lead to hearing loss!!!!
The longer you are exposed to these loud sounds, the tiny hairs are damaged permanently!!!!!
They do not grow back if they are damaged!!!!
Sounds above 80db are considered potentially hazardous

12. Sound is measured by decibels
Sound is measured by decibels. Here are some examples of different sounds.
Sounds dB SPL
Rocket Launching
Jet Engine
Thunderclap, Air Raid Siren 1 Meter
Jet takeoff (200 ft)
Rock Concert, Discotheque
Firecrackers, Subway Train
Heavy Truck (15 Meter), City Traffic
Alarm Clock (1 Meter), Hair Dryer
Noisy Restaurant, Business Office
Air Conditioning Unit, Conversational Speech 60
Light Traffic (50 Meter), Average Home 50
Living Room, Quiet Office
Library, Soft Whisper (5 Meter)
Broadcasting Studio, Rustling Leaves 20
Hearing Threshold

13. What else does loud noise affect?
Noise not only affects hearing. It affects other parts of the body and body systems.
It is now known that noise:
Increases blood pressure
Has negative cardiovascular effects such as changing the way the heart beats
Increases breathing rate
Disturbs digestion
Can cause an upset stomach or ulcer
Can negatively impact a developing fetus, perhaps contributing to premature birth
Makes it difficult to sleep, even after the noise stops
Intensifies the effects of factors like drugs, alcohol, aging

14. Protect Yourself from Noise
Limit your exposure
Pump down the volume!
Educate yourself and others
Have your hearing tested regularly
Wear ear protection