Nettling Sound ELab

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sound compression expansion amplitude wavelength frequency hertz pitch sound barrier sonic boom intensity sound level decibels echoes reverberation

IMPORTANT NOTE:
Our class researched the online sources
Bill Nye the Science Guy®, Fact Monster,
What is shown on this page are our study notes from what we learned.
Please visit the actual sites for accurate, complete information!

What is sound? | What is the speed of sound? |
How does sound change, and how is it measured? | The Bottom Line | Links

What is sound?
Sound is energy produced and created by vibrations. The vibrating causes neighboring particles to bump into each other. Those bumps move out in waves away from the vibrations. If you pluck the string of a guitar, the string starts vibrating and causes the air around it to vibrate, too. The vibrations travel through the air to your eardrum -- and you hear sound. Sound travels in waves by disturbing the particles of a material medium. Sound is different from light in that it needs a medium (solid, liquid, or gas) in which to travel. Sound waves cannot travel through a vacuum.¹

Materials around the source of the sound can absorb sound. When sounds are absorbed, they are quieter. When sounds bounce back, they reflect. Smooth, hard surfaces like walls reflect sounds. When sound waves hit a hard surface and reflect back, the sound we may hear is called an echo.

The key thing to remember is that sound is really vibrations.

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What is the speed of sound?
Scientists have determined that the speed of sound is about 700 miles per hour. That is much slower than light, which explains why you hear thunder after you see the lightning in a thunderstorm.

Sound travels faster on hot days than on cold days. Sound travels four times faster in water, and even faster still through solids than through air. Some jets can travel faster than sound. When a jet goes faster than the speed of sound, it breaks the sound barrier and causes a sonic boom.²

The key thing to remember is that sound moves fast, but not nearly as fast as light.

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How does sound change, and how is it measured?
The rate of vibration affects the pitch (highness or lowness) of a sound. It is the result of the frequency of the sound wave. The volume (loudness) of the sound is the result of the amplitude of the sound wave and is measured in decibels. Any sound above 80 decibels can cause hearing loss. Sounds of 120 decibels or higher can cause ear pain.

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The Bottom Line

Sound is made by vibrations.

Sound travels through materials in waves.

Ears are specialized structures designed to receive sound.

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Related Links

Alexander Graham Bell's Path to the Telephone

BBC: ReviseWise Science

Bethune Academy 5th Grade

Dallas Symphony Orchestra Site for Kids

Encarta Encyclopedia

Fact Monster: Sound, Sound Waves, Musical Sounds

KidsKonnect Light and Sound

NASA SciFiles: Sound

Sound is Energy

The Soundry

Bibliography

¹ "http://www.factmonster.com/ce6/.html." The Columbia Electronic Encyclopedia.
   © 1994, 2000-2006, on Fact Monster.
   © 2000–2007 Pearson Education, publishing as Fact Monster.
   15 Feb. 2007 <http://www.factmonster.com/ce6/sci/A0871106.html>.

² Kelly, Kate and Zeman, Anne. Everything You Need to Know About Science Homework. Scholastic,
   New York, NY, 1994.

³Bill Nye the Science Guy®, "Sound", 2005, http://www.billnye.com/ (accessed February 17, 2007).

Citing: This webpage is a location for our investigation and study notes. We are not experts or scientists; we are students. Please do not cite!

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