Extreme Sounds by Tarissa and Sabrina

We live in one of the world's noisiest cities, New York City. There's so much going on here that it's hard to hear yourself think. Our DragonflyTV question was: Are the sounds of the city as loud as we think they are?

What did we do?
We picked a bunch of locations around the city. We headed to the library, the subway, the Empire State Building and an airport, just to name a few. We ranked each area by how loud we thought it was. We also took a reading with a special meter that measures the decibel level - decibels are a special scale for loudness. We wanted to see how the numbers compared.

What did we find out?
We charted the real reading and our rankings for each location. Some of the readings surprised us. We thought the library was really quiet, but it had a decibel reading of 46! At the other extreme, a barking dog and a marching band turned out to be louder than either the subway or the airplane. One thing we learned is that loudness depends on how close you are to the sound source.

What can you do?

• Investigate loud sounds in your school. Your own hands can be your loudness meter! Make a soft shooshing sound by gently rubbing your palms together. Snap your fingers. Clap your hands. These are your reference sounds. Go to different parts of the school and make these three sounds. If you can hear the shooshing, that place is quiet. If you can't hear the shooshing but can hear the fingersnaps, that place is moderately loud. If you can't hear fingersnaps but can hear clapping, the place is loud. If you can't hear clapping, the place is DANGEROUSLY loud. You need ear protection!
   
  
• Is there a place with zero decibels? Find a few quiet spots in your city and see how quiet they really are. Do you get used to background noises like computers, TV, traffic hums or house creaks? What other noises are you tuning out?
   
  
• Investigate how sounds fade with distance. Set a radio to a low volume then walk away until you can't hear it anymore. Measure the distance or count the steps. Repeat the test with increasing volumes. What do you notice? Does "twice as loud" mean you walk twice as far away?
   
  
• Use this sound investigation as a science fair project idea for your elementary or middle school science fair! Then tell us about it!
   
  

	SciLinks More on the Properties of Sound Go to the DFTV Boards, and tell us about your science investigation.