1. Chapter 21 The Nature of Sound Section 1 – What Is Sound? pp. 600 - 605

2. TERMS TO LEARN Wave – a disturbance that transmits energy through matter or space Wave – a disturbance that transmits energy through matter or space Medium – a through which a wave can travel Medium – a substance through which a wave can travel

3. TERMS TO LEARN Outer ear – the part of the ear that acts as a funnel to direct sound waves into the middle ear Outer ear – the part of the ear that acts as a funnel to direct sound waves into the middle ear Middle ear – the part of the ear where the amplitude of sound vibrations is increased Middle ear – the part of the ear where the amplitude of sound vibrations is increased Inner ear – the part of the ear where vibrations created by sound are changed into electrical signals for the brain to interpret Inner ear – the part of the ear where vibrations created by sound are changed into electrical signals for the brain to interpret

4. QUICK LAB Complete the Quick Lab on p. 601 of your text. Record your observations in your notebook.

5. WHAT IS SOUND? Sound is produced by vibrations Sound is produced by vibrations Sound travels as longitudinal waves. Sound travels as longitudinal waves. Sound is a mechanical wave. It requires a medium to travel through. Sound is a mechanical wave. It requires a medium to travel through.

6. MAKING SOUND VS. DETECTING SOUND What is the difference between making sound and detecting sound? What is the difference between making sound and detecting sound? If a tree falls in the forest and no one is around to hear it, does it make a sound? If a tree falls in the forest and no one is around to hear it, does it make a sound? Sound was created, but it wasn’t detected. Sound was created, but it wasn’t detected.

7. HOW DO YOU DETECT SOUND? 1. Sound waves vibrate the eardrum. 2. This vibration makes the hammer, anvil and stirrup (bones in the ear) vibrate. 3. The vibrations of the stirrup make the entrance to the inner ear (the oval window) vibrate.

8. HOW DO YOU DETECT SOUND? 1. These vibrations create waves in the liquid inside the cochlea. The movement of this liquid causes the cilia (the tiny hairs inside the cochlea) to vibrate. 2. This bending of the cilia stimulates nerves which sends electric signals to the brain.

9. HOW THE EAR WORKS The pinna of the outer ear collects sound waves and funnels them into the ear canal. The pinna of the outer ear collects sound waves and funnels them into the ear canal. The hammer, anvil and stirrup act as levers to increase the size of the vibrations. The hammer, anvil and stirrup act as levers to increase the size of the vibrations. In the inner ear, the vibrations created by sound are changed into electrical signals for the brain to interpret. In the inner ear, the vibrations created by sound are changed into electrical signals for the brain to interpret.

11. HEARING LOSS The parts of the ear must work together for you to hear sounds. The parts of the ear must work together for you to hear sounds. If any of the parts is damaged or does not work properly, hearing loss or deafness may result. If any of the parts is damaged or does not work properly, hearing loss or deafness may result. Tinnitus is one of the most common types of hearing loss. Tinnitus is one of the most common types of hearing loss.

12. HEARING LOSS Tinnitus results from long-term exposure to loud sound (i.e. concerts) Tinnitus results from long-term exposure to loud sound (i.e. concerts) Loud sounds can cause damage to the hair cells and nerve endings in the cochlea Loud sounds can cause damage to the hair cells and nerve endings in the cochlea Damage to the cochlea or any part of the inner ear results in permanent hearing loss. Damage to the cochlea or any part of the inner ear results in permanent hearing loss.

13. WAYS TO PREVENT HEARING LOSS Wear ear protection while working with loud machinery. Wear ear protection while working with loud machinery.

14. WAYS TO PREVENT HEARING LOSS Turn down your ipod. Turn down your ipod.