1. Sound

2. What Causes Sound? p. 322 Sound is produced by an object that VIBRATES
Sound waves are COMPRESSIONAL waves. Compressional waves are made of COMPRESSIONS and RAREFACTIONS.
A wavelength in a compressional wave is made of ONE COMPRESSION AND ONE RAREFACTION.

3. What Causes Sound? p. 322

4. The Speed of Sound p
Sound waves travel through solid, liquids, and gases.
MEDIUM – material in which a sound wave moves
The speed of a sound wave depends on two things: MEDIUM and TEMPERATURE.
AIR is the most common medium through which sound travels.
Sound travels slowest in GASES and fastest in LIQUIDS and SOLIDS.

5. The Speed of Sound p
As temperature INCREASES, its atoms and molecules move faster, and collide with each other more frequently.
Sound travels FASTER as the temperature increases.

6. Intensity and Loudness p. 327-329
INTENSITY – amount of energy that flows through a certain area in a specific amount of time
As a sound wave travels away from the source of the sound, the INTENSITY of the wave decreases as the wave spreads out.

7. Intensity and Loudness p. 327-329
LOUDNESS – human perception of sound intensity
As intensity INCREASES, the loudness INCREASES.
DECIBEL (dB) – unit for sound intensity levels. Above 120 dB may cause pain and permanent hearing loss.

8. Frequency and Pitch p. 330
Highness or lowness of a sound is called PITCH.
FREQUENCY – measure of how many wavelengths pass a particular point in each second
Measured in HERTZ (Hz)
The HIGHER the FREQUENCY, the higher the pitch.
The LOWER the FREQUENCY, the lower the pitch.

9. Frequency and Pitch p. 330
The human ear can hear sound waves with frequencies from about 20 Hz to 20,000 Hz.
ULTRASONIC – sounds with frequencies above 20,000 Hz. (used to estimate size, shape, and depth of underwater objects)
INFRASONIC or SUBSONIC – sounds with frequencies below 20 Hz.

10. Doppler Effect p
Doppler Effect is CHANGE IN PITCH OR FREQUENCY THAT OCCURS WHEN A SOURCE OF SOUND IS MOVING RELATIVE TO A LISTENER
Examples????
The faster the change in position, the greater the change in FREQUENCY and PITCH.

11. Using Sound p
ECOLOCATION – the process of locating objects by emitting sounds and detecting the sound waves that are reflected back.

12. Using Sound p
SONAR – system that uses the reflection of underwater sound waves to detect objects
Used for: submarines and mine detection, depth detection, commercial fishing, diving safety, and communication at sea
ULTRASOUND – sound waves directed towards a target area of patient’s body