Ears

Hearing Your ears are the sense organs that respond to the stimulus of sound. The ears convert the sound to nerve impulses that your brain interprets.

How are sounds made? By a material that is vibrating or moving back and forth. EX: guitar strings, insect wings, splashing water The waves from the sound move outward from the source. Sound waves can travel through gases (air), liquids (water), and solids (wood). When you hear a voice, sound waves have traveled from the person’s voice to your ears.

SOUND WAVES Short waves  A little space between peaks of waves HIGH SOUNDS Long waves  A lot of space between peaks of waves LOW SOUNDS http://science.education.nih.gov/supplements/nih3/hearing/activities/lesson3.htm

3 Sections of the Ear Outer Ear Middle Ear Inner Ear

The Outer Ear: Catch the Wave The main job of the outer ear is to collect sounds. Shaped like a funnel to gather sound waves. Sound enters through down the ear canal and reaches the eardrum. EARDRUM  a membrane that vibrates when sound waves strike it. Vibrations from the eardrum in the outer ear pass to the middle ear.

The Middle Ear: Good Vibrations The eardrum separates the outer ear from the middle ear The eardrum vibrates when sound waves strike it. Vibrations from the eardrum pass to the three smallest bones in the body. Hammer Anvil Stirrup

The Inner Ear: Nerve Signals Start Here Vibrations from the stirrup are passed to the fluid in the cochlea of the inner ear. COCHLEA – snail-shaped tube that is lined with receptors that respond to sound Vibrations in the fluid of the cochlea stimulate the receptors. Receptors send impulses through sensory neurons to the brain where the sound is interpreted.

The Inner Ear and Balance Semicircular Canals: Structures in the ear that control your sense of balance. Canals are full of fluid and hair-like extensions.

BALANCE When your head moves, the fluid moves. The moving fluid makes the hairs bend. The bending produces nerve impulses in sensory neurons. The impulses travel to the cerebellum. The cerebellum senses you are losing balance and sends an impulse to the muscles to help restore the balance.

Why do your ears pop? The eustachian tube — equalizes the air pressure between the middle ear and the outside world. When your ears pop while yawning or swallowing, the eustachian tubes are adjusting the air pressure in the middle ears.

SMELL