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Lesson 13 – Changing How Sound Travels

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Read About Changing How Sound Travels

Vocabulary

Read the vocabulary terms to understand the reading better.

To absorb is to take in or soak up.

An echo is the repetition of a sound caused by sound waves bouncing off a surface.

Echolocation is when an animal sends sounds that bounce off surfaces to tell them where objects are.

Energy is the ability to do work or to make something move or change in some way.

Reflection occurs when light travelling through one material bounces off a different material.

The surface is the outside or top part of something.

Reflected Sound

Have you ever heard an echo? An echo is sound reflecting, or bouncing off, a surface. Light will reflect off a mirror. Sound will reflect off a surface, too. Sound will keep bouncing around until it loses its energy.

Some animals use sound in a special way. Bats and whales send out sounds that bounce off surfaces. The echoes tell them where the objects are. Using sound in this way is called echolocation.

Absorbed Sound

Can you stop sound from travelling far? Can you stop sound from reflecting? Can you make sound quieter? Materials that are not smooth or hard can help you do these things.

Have you ever been in an empty house that no one lives in? You probably noticed a lot of echoes. Soft materials absorb sound. They stop echoes. An empty house has no soft materials to absorb the sound. Adding carpets, furniture, and drapes helps quiet the sound.

Now Show What You Know!

Complete some questions about the reading selection by clicking “Begin Questions” below.