Why do we sometimes hear echoes, but not others? Have you ever noticed that some places are really great for echoes? Even your footsteps can sound neat in these spots. Have you ever been in one of those places and shouted, “Hello,” and heard a distant “Hello-llo-llo” in response?
Sound travels in waves, and sound waves can bounce. Just like a basketball, sound bounces better off of hard surfaces like a floor or a wall. If you try to bounce a basketball on a soft surface like a pile of pillows or blankets, it won’t work very well. The same is true of sound. If a sound wave hits a soft surface, it does not bounce back. Instead, the sound wave is absorbed by the soft surface.
In your house, sound doesn’t echo very well because there are curtains, carpeting, blankets and plenty of soft surfaces to absorb the sound. But outside there is a combination of hard and soft surfaces. So get outside and do some echo experiments of your own.
One important rule for experimenting with echoes is not to scream. A scream sends a message that something is wrong, and you never want to scare anyone. Instead of screaming, shout something friendly, like “Hello” or “Have a nice day.” Or try something silly, like “Yodel-ay-hee-hoo” or “Olly olly oxen free.” You can also experiment with other sounds like hammering a nail (but get help from an adult first), clapping or even banging a spoon on a pan.
You can also try standing in front of your house facing the street. Make a loud noise. Turn around and face your house, then repeat the noise. Was there an echo? Did it sound different by changing directions? Try the same in the back yard, or on the side of the house. Do you hear an echo? Is it loud or soft?
Think of other locations you can go to test an echo. What if there is snow on the ground? Will that make a difference? You can keep a journal of what you discover.
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