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P. 103
Activity 7
Demonstrating an echo
FOR ONLINE READING ONLY
1. Enter an empty hall and stand at least 17m from one of
the walls as shown in Figure 14.
2. Shout loudly. What do you hear?
3. Write the results of the action you performed.
Figure 14: Demonstrating an echo formation
When you stand in an empty hall and shout loudly, you hear
your sound repeating. For example, if you say ‘hello’, after a
few seconds, you hear ‘hello’ again. This repeated sound is
called an echo. What happens is that sound waves travel from
your mouth through the air and hit a hard surface like a wall,
and bounce back, causing you to hear the sound you initially
made. Sound is reflected when it hits a barrier or a hard surface
like a wall or rock.
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