Sound and Water

Sound in water and sound in air are both waves that move similarly and can be characterized the same way. Sound waves can travel through any substance, including gases (such as air), liquids (such as water), and solids (such as the seafloor).

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Did you know that sound cannot exist if it doesn’t have something to travel through? For example, sound cannot travel through outer space because it is a vacuum that contains nothing to carry sound.

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Even though sound waves in water and sound waves in air are basically similar, the way the sound levels in water and sound levels in air are reported is very different, and comparing sound levels in water and air must be done carefully.

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When we describe a sound as loud or soft, scientists say that the sound has a high or low amplitude or intensity. Amplitude refers to the change in pressure as the sound wave passes by.

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If you increase the amplitude of a sound, you are making it louder, just as you do when you turn up the volume on your radio. If you decrease the amplitude, you are making the sound softer, just as when you turn down the volume.

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We wanted to see how this happens in the real world, so we did a music experiment with water, drum sticks, and metal bowls! First, we placed some metal bowls into the water table. Using drum sticks, we tapped the bowls, and talked about some of the sounds we heard.

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We used words such as ping, loud, soft, echo. metallic, and thunder. Next, we added water to the water table, and placed the bowls inside. We again tapped the bowls, and talked about any differences we observed. Some students found that they sounded softer in the water, while others thought they sounded louder. For this half of the activity, we used words such as amplitude, sound waves, liquid, and air to describe what we were hearing.

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