2.  Making Sound Waves:  A sound wave begins with a vibration.  How Sound Travels:  Like other mechanical waves, sound waves carry energy through a medium without moving the particles of the medium along.

3.  Reflection:  Sound waves may reflect when they hit a surface  Diffraction:  Sound waves can also diffract, bend around corners, this is why you can hear someone talking around the corner before going around the corner.  Interference:  Sound waves may meet and interact with each other.

4.  Elasticity :  If you stretch a rubber band and then let it go, it returns to its original shape; However, when you stretch modeling clay it stays stretched. Elasticity is the ability of material bouncing back after being disturbed.  Density:  Density is how much matter, or mass there is in a given amount of space, or volume  Temperature:  In a given medium, sound travels more slowly at a lower temperature. At a low temperature the particles of a medium more move slowly then at a high temperature.

5.  Energy of a Sound Wave:  In general, the greater the energy used  to make the sound, the louder the sound.  Distance From a Sound Source:  Loudness increases the closer you are  to the sound source.  Measuring Loudness:  The loudness of different sounds is compared  using a unit call the decibels (dB).

6.  Pitch and Frequency:  Sounds with a high frequency have a high pitch, sounds with a low frequency have a low pitch.  Changing Pitch:  Pitch is an important property off music because music usually uses specific pitches called notes.

7.  What Causes The Doppler Effect:  When a sound source moves, the frequency of the waves changes because the motion of the source adds to the motion of the waves.  What Causes Shock waves:  When the plane travels almost as fast as the speed of sound the sound barrier is broken

8.  Fundamental Tones and Overtones:  You may recall that standing waves occur when waves with just the right frequency interfere as they reflect back and forth.  Resonance :  Resonance affects the sound quality of a musical instrument by increasing the loudness of certain overtones.

9.  Stringed Instruments:  The guitar and violin are stringed instruments.  Wind Instruments:  Wind instruments include brass instruments; such as trumpets and woodwind instruments such as clarinets.  Percussion Instruments:  Percussion instruments include drums bells cymbals and xylophones.

10.  Acoustics is used in the design of correct halls to reverberation and interference.

11.  Outer Ear:  The outer part of your ear acts as a funnel and collects sound.  Middle Ear:  Behind the ear drum is the middle ear, the middle ear contain 3 of the smallest bones in your body called the hammer, the anvil, and stirrup.  Inner Ear:  A membrane separates the middle ear form the inner ear; the third section of the ear.

12.  Causes of Hearing Loss :  Hearing loss can occur suddenly if the eardrum is damaged or punctured.  Hearing Aid:  For some types of hearing loss the hearing aids can restore some ability to hear.

13.  Microphone: The microphone converts acoustic sound energy into electrical energy. Some hearing aids use two microphones to help separate background noise.  Processor: The processor digitizes the acoustic sound, then separates background noise from speech. Both are processed to make speech clearer and to reduce the interference of background noise.  Amplifier: The amplifier boosts the processed signal according to the pattern and severity of your hearing loss, as well as the amount of background noise.  Speaker: The speaker converts the electrical signal back into acoustic sound and directs the sound into your ear canal. Some models have the speaker placed in your ear canal. Some use a tube that connects the speaker to plug or custom ear mold. Others have the components housed in a custom-fitting shell.  Battery compartment: The battery powers the electronic components. The battery compartment is used to turn the hearing aid on and off.  Optional controls: Some models have a volume control to regulate the volume. Others have a program control, enabling you to change the processing for different listening situations, such as high background noise or music. These controls are available on the hearing aids or on a remote control.

14.  Bats:  Bats can use ultrasound waves with frequencies up to 100,000 Hz to move around and hunt.  Dolphins, Porpoises, Whales:  Dolphins, porpoises, and whales something have to hunt in the darkness so like the bats they use echolocation ultrasounds up to 150,000 Hz.

15.  Sonar:  A system that uses reflected sounds wave to detect and locate objects underwater is called sonar.  Ultrasound Imagine:  Doctors use ultrasound imaging to look inside the human body.

16.  Sound quality is a blend tones.

17.  Ultrasound is used to look inside humans, animals, and other objects. For example, if a woman is expecting it will allow you to see the baby inside.

18. What does a sound wave begin with? A. a noise B. a vibration C. a metal object D. none of the above

19. The loudness of different sounds is compared using a unit call ______________. A. boom B. meter C. decibels D. deadbeats

20. What part of your ear acts as a funnel and collects sound? A. middle ear B. inner ear C. outer ear D. ear drum