If you tap a drum, it will create a sound wave, and make a noise. If you hit the drum again but harder--let's say you bang it--it will create a sound wave that travels further, and make a louder noise. The bang's sound wave traveled farther than the tap's, because it moved the particles in the medium--in this case the air--farther. How far a wave causes the particles in a medium to move is called the amplitude of the wave.
Watch this animation to find out more about energy and amplitude, and also about volume. As you watch the segment, you might want to check the definition of specific terms. In addition to the glossary words listed above, the term longitudinal wave will be used.
Stop the animation at any time, watch it again, or read the transcript.
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Do you hear that? That is energy being transferred through a medium, in a wave pattern, to your ear. That is sound.
Sound is energy that vibrates a medium, and those vibrations travel in waves. The way those waves interact with the medium determines the way the sound, well, sounds, One of the most obvious sound qualities is volume. And that volume--the "loudness" of a sound--depends on energy.
If the energy being transferred is low, the particles get pushed a small distance, and the sound is quiet. If the energy being is high, the particles are pushed a farther distance, and the sound is loud.
And we can measure this by measuring the sound wave's amplitude--the distance each particle is pushed from its resting place.
Take a drum and hit it. The energy from your hand transfers to the drum, which vibrates the air around it, making a sound. Now increase that energy--hit the drum hard, and the drum pushed the air even farther. Same sound, but the higher amplitude means it's louder and can travel farther.
So, hit the dance floor and pump up the amplitude.
In the space below, write one sentence describing how a loud sound is different from a quiet sound. Then write a sentence that describes the relationship between volume and amplitude.