Why does sound travel so far over water?
In: Physics
Great question!
First, we have to start with what sound IS to understand how it travels. Sound is essentially a wave. When you drop a pebble in perfectly calm water, you see waves coming off the point, right? That’s a lot like sound. When you snap your fingers, you are “rippling” the air, which travels to your ear drum. Your ear converts the ripples into signals that go to your brain.
If sound is a wave that goes through the air, then we also know what can interrupt that wave. Standing in a room, the wave will bounce off anything in the room as well as the walls, floor, and ceiling. Depending on the shape of the object and the material, it’ll reflect different amounts of the wave. In some cases, it’s absorbing the wave! Shouting across a field is difficult because of all the irregular objects on the ground scattering and/or absorbing that air wave (grass, rocks, etc…).
Water reflects air pretty easily because it’s a lot more dense than air. For all intents and purposes, we can think of water as being a very hard, smooth, surface. A lot of the air is allowed to move very easily across that surface and therefore the wave travels much farther.
There are a lot of other factors too, like wind. Because sound is really just a wave traveling through air, wind can jumble it up and take it really far away. Lakes also tend to have banks, which reflect the air back over the water, so it keeps the sound channeled onto the lake.
At the end of the day, think about sound as a wave that radiates from a source. You hear that wave and all the reflections of that wave from everything around you.
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