1. 6 th Grade Science ©j.slater 2011 Adapted from K.Reed

2. Sound is a form of energy caused by vibrations. Vibrations = rapid back and forth movement of molecules. Sound energy is transmitted by vibrating an object.

3. Activity #2: Stand in a circle S S = sound source The students are to stand in a circle. The teacher will stand in the center of the circle. Listen for your teacher to make a sound. Raise your hand if you hear it. What are we proving in this experiment?

4. Place your fingers on the front of your throat & recite the alphabet. Vary your speed, pitch, and volume. Record your observations. BE GENTLE Low & Slow => short vibrations, more intense. High & Fast => long vibrations, not as intense. Whisper => no/little vibrations.

5. Pitch Pitch is a measure of how high or low a tone sounds to your ear. Pitch depends on the frequency of the sound waves Frequency = the measure of the number of waves that pass in a given time.

6. Greater frequency = more waves= higher pitch Low Frequency Low Pitch Middle Frequency Middle Pitch High Frequency High Pitch

7.  Have you ever placed your hands over your ears because something was too loud? Intensity/loudness/ volume/ depends on how much energy was used in producing the sound. You use a lot more energy to yell than you do to whisper. If you want to play a musical instrument loudly, what do you need to do? Piano: Guitar: Drum: Trumpet: Pound on the keys Strum the keys hard Hit hard Blow hard

8. Think About it!  Think about the gym. What are the floor, walls, and ceiling made of?  Think about the library. What are the floors, walls, and ceiling made of?  Why do you think they are made of some different materials?  What purposes do the rooms serve?  How does this relate to sound? Sound waves can be reflected off surfaces or absorbed by them.

9.  Absorption: The ability to take in or dampen.  Certain materials “soak” up sound.  To keep certain area quiet (like libraries), certain materials are placed in the room to absorb noise. Examples of sound absorbing materials: carpet, material, furniture, cloth, Styrofoam

10.  If sound is reflected from an object, we hear an echo.  In a large auditorium (like gyms), sounds are reflected from walls, ceilings, wooden floors, metal structures, etc.  This is known as reverberation.  Too much reverberation is unpleasant, but a little gives sound its fullness.  Acoustical Engineers try to design buildings with reflecting and absorbing materials to help sound travel and still control reverberation.

11.  Sound travels fast through solids Ex: Dental drill transmitted clearly through bones of skull.  Sound travels slower through liquids and gases. Ex. Talking to someone under water.  Sound does not travel in a vacuum.  A vacuum is a place with no air.

12. Why can’t sound travel in a vacuum? No air molecules to carry sound waves. No air in space; therefore, no sound. How do astronauts communicate? Radios inside their helmets