1. SOUND Can You Hear Me Now?

2. GOAL 5: Students will describe the characteristics of and investigate Wave Motion, Sound, and Light.  Objective 1: Differentiate between Transverse and Longitudinal Waves.  Objective 2: Describe the relationship between Speed of a Wave, Frequency of a Wave, and Wavelength.  Objective 3: Investigate the nature of Sound in terms of Wave Motion.

3. WAVES are caused by VIBRATIONS  SOUND is produced by an object that VIBRATES.  SOUND WAVES are COMPRESSIONAL WAVES  A SOUND WAVE moves through matter as collisions between the molecules in the matter transfers ENERGY from place to place.

4. COMPRESSIONAL Waves are also called LONGITUDINAL Waves

5. SPEED OF SOUND o SOUND WAVES travel at different speeds through different MEDIUMS and at different TEMPERATURES. o SOUND WAVES CANNOT travel through empty space where there are no particles to collide with. o SPEED OF SOUND IN AIR: approx. 343 m/s (767 mph) o SPEED OF SOUND IN WATER: approx. 1,498 m/s (3,350 mph) o SPEED OF SOUND IN STEEL: approx. 5,200 m/s (11,632 mph) o SOUND WAVES travel FASTER in WARMER TEMPERATURES VARIES

6. INTENSITY  The amount of ENERGY transferred by a Sound Wave is the INTENSITY of the Sound Wave. (Amplitude)  LOUDNESS is how people perceive INTENSITY.  INTENSITY is measured in DECIBELS.  Baby Crying = 90 -115 dB  Cat Purring = 25 dB  Airplane taking off = 140 dB

7. DECIBELS = dB

8. PITCH & FREQUENCY PITCH is the human perception of the FREQUENCY of a Sound Wave. FREQUENCY = the number of wavelengths per sec. FREQUENY is measures in HERTZ (Hz). Lower Frequency Higher Frequency

9. Christian Doppler http://www.youtube.com/watch?v=Man9ulEYSgk&feature=related In 1842 – Austrian physicist Christian Doppler described what became known as the “Doppler Effect” as “A change in Pitch or Frequency that occurs when a source of a sound is moving in relation to the listener.”

10. DOPPLER EFFECT

11. INFRASONIC vs. ULTRASONIC  HUMANS can hear between 20 and 20,000 Hz.  DOGS and BATS have ULTRASONIC hearing – they can hear sounds “Beyond” what humans can hear.  Some things like earthquakes can make INFRASONIC, or SUBSONIC, sounds “Below” what human can hear.  ULTRASONIC waves can even be used by doctors to see inside the body.

12. ECHOLOCATION Some animals use sound waves to locate and catch their prey.

13. THE HUMAN EAR