SOUND

Nature of Sound

Objectives: Determine the ultimate source of sound

Discuss properties of sound.

Label and discuss parts of the ear.

All sound comes from vibrating objects

Sound is a compressional wave.

Sound waves spread out in all directions away from the source.

The speed of sound depends on the medium.

Sound travels fastest in solids because the particles are closer together.

Sound travels slowest in gases because the particles are spread far apart.

The speed of sound also depends on the temperature of the medium.

An increase of the temperature of the medium will increase the speed of sound.

The 3 major parts of the ear are the outer, middle, and inner ear.

The outer ear’s purpose is to gather sound and funnel it to the middle ear.

The outer ear is made up of the visible part of the ear, the ear canal, and the eardrum.

The middle ear’s purpose is to amplify sound.

The middle ear is made up of the anvil, hammer, and the stirrup.

The inner ear’s purpose is to convert sound waves to nerve impulses.

The inner ear is made up of the cochlea.

There are four stages of hearing.

a. gather sound

b. amplify sound

c. convert sound to impulses

d. brain interprets impulses

Properties of Sound

Objectives – Determine the amplitude of a sound wave.

Describe the intensity and pitch of a sound

wave.

Describe the Doppler Effect.

1. The amount of energy of a wave is its amplitude.

2. The amplitude of a sound wave depend on how tightly packed the molecules are in the compression and rarefaction.

3. The intensity of a sound wave is the amount of energy that flows at a particular time.

4. Intensity will determine how far a wave will travel and how far away it can be heard.

5. The human perception of intensity is loudness.

6. Loudness is measured in decibels.

7. Pitch is related to frequency.

8. Pitch is how high or how low a sound seems to be.

9. A high frequency would be a high pitch.

10. The range of hearing of a human is from 20 to 20,000 hz.

11. Sounds above 20,000 hertz are ultrasonic.

12. Sounds below 20 hertz are infrasonic.

13. Although you can not hear these sounds, you usually feel them in your body.

14. The Doppler effect is the change in pitch or wave frequency due to a moving wave source.

15. As a sound approaches an observer, it appears to have a higher pitch and a higher frequency.

16. As the sound passes the observer, it appears to have a lower pitch and a lower frequency.

17. With the Doppler effect, greater speeds have greater changes in frequency, so the Doppler effect is more dramatic with a race car than an ambulance.

18. The decibel scale ranges from 0 to 150 db where 120 causes damage to hearing.

19. What properties change when you turn up the volume on the radio?

Velocity, intensity, pitch, amplitude, frequency, wavelength, loudness)

20. What are two other used of the Doppler Effect besides sound?

weather and radar guns

Using Sound

1. There are many different uses for sound.(entertainment, warning signals, etc.)

2. Bats use echolocation as a way of locating prey and hunting by producing ultrasonic sound waves that bounce off of the object and reflect back to the bat to identify the object’s location.

3. Sonar (sound navigation ranging) is a system that uses the reflection of underwater sound waves to detect objects.

4. Radar (radio detecting and ranging) is a system that uses the reflection of radio waves to detect objects.

5. Ultrasonic sound waves are also used to clean jewelry, clean glassware, and in medicine.

6. Ultrasound imaging is used to produce images of internal structures and detect and monitor conditions such as pregnancy, cancer, and types of heart disease.

7. Ultrasound and X-rays are similar because they both produce images.

8. X-rays are used for bones and hard tissue.

9. Ultrasound is used for soft tissue because the ultrasonic waves would be absorbed by hard tissue and air.

10. The echoing effect produced by many reflections of sound is called reverberation.

11. Scientists and engineers who study acoustics understand how the following 3 aspects of a room can affect the sound.

a. size

b. shape

c. furnishing