Sound Waves and Hearing

1. Sound Waves and Hearing Standard 8-6.5 Explain hearing in terms of the relationship between sound waves and the ear.

3. Three Basic Parts of the Ear • Outer Ear • Funnels sound waves or collects waves • Middle Ear • Transmits the sound waves inward • Inner Ear • Converts the sound waves into a format that your brain can understand.

4. Three Basic Parts of the Ear

5. Outer ear (sound collector) • Sound waves are gathered by the outer ear. • Made up of the ear, the ear canal, • The outer ear is shaped to help capture the sound waves (energy transferred in particles of air) and sends them to the ear canal, which transfers them to the eardrum.

6. Middle ear (sound amplifier) • The middle ear amplifies sound waves. • It consists of the eardrum, which is a small, tightly stretched, drum like membrane. • The vibrations of air particles cause the eardrum to vibrate. -Contains the three smallest bones in the human body. • Hammer, Anvil Stirrup

7. -Vibrations from the eardrum are transmitted to the three small bones which transmit the vibrations to the inner ear.

8. Normal Ear Drum

9. Inner ear (converts sound waves so brain can understand) • The inner ear transmitsvibrations from the bones of the middle ear to a cavity filled with liquid (cochlea). • Vibrations in the liquid cause tiny hairs to vibrate. - The tiny hairs in the inner ear vibrate as the liquid vibrates. - The vibrating tiny hairs transmit the energy to nerves attached to the hairs. - The nerve impulses are transmitted to the brain and interpreted as “hearing.”

11. How we hear Sound is collected by the visible part of the ear and directed through the outer ear canal. The sound makes the eardrum vibrate, which in turn causes a series of three tiny bones (the hammer, the anvil, and the stirrup) in the middle ear to vibrate. The vibration is transferred to the snail-shaped cochlea in the inner ear. The cochlea is lined with sensitive hairs which trigger the generation of nerve signals that are sent to the brain.

12. Basic Concepts of Sound • The disturbances that travel in sound are called vibrations. • Remember, sound waves require a medium to travel and are LONGITUDINAL WAVES!!!

13. Sound and Pitch • Pitch distinguishes between the highness and lowness of a sound. • The pitch of a sound depends on the frequency of a sound wave. The key farthest to the left on the piano is attached to the longest string. This key plays the note with the lowest pitch.

14. Low Pitch • Low Pitched sounds: • Vibrations follow each other slowly (low frequency) • Low pitch = Low frequency • Examples: Tubas, base piano keys and engines of heavy trucks.

15. High Pitch • High Pitched sounds: • Vibrations follow each other more rapidly (high frequency) • High pitch = High frequency • Examples: Ambulance as it passes, birds singing and smoke alarms.

17. VOLUME – WHAT IS IT? Sound waves with large amplitudes push on the eardrum with more force and are heard as loud sounds. Sound waves with small amplitudes push on the eardrum with less force and are heard as soft sounds.

19. IN YOUR JOURNAL, ANSWER THESE QUESTIONS IN A PARAGRAPH FORM. • Explain the difference between PITCH and VOLUME. Be sure to include information on what is pitch and how sound waves travel. (use the words frequency and amplitude in your info) • In a step-by-step format, if you heard a lion roar right now, explain how the sound ends up “recording” in your brain. Start with sound waves traveling through the air and hitting your ear. FINISH THIS ASSIGNMENT