How is it that sound travels the slowest in gas (which is all around us) but when we’re underwater we can’t hear much of anything coming from the surface?

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I mean, shouldn’t we be hearing things coming from the surface when we’re underwater, since the wave just caused the molecules which are closer together in liquid than in gas to hit eachother?

In: Physics

Most of the sound wave bounces away when it hits the water. What’s left does make the water molecules move but has very little energy to go deep under water and the sound fades away quickly.

Sound doesn’t transfer very efficiently between air and water – most of the sound energy that hits the water surface will be reflected from it rather than being transmitted into the water. This is due to the large difference in [acoustic impendence](https://en.wikipedia.org/wiki/Acoustic_impedance) between the two fluids.

Our ears have evolved to hear sounds through the air, and aren’t great under water. In fact, I believe the sound tends to bypass the ear drums and instead tend to vibrate our mostly-water insides more instead.

That said, sound can travel great distances through water when that sound originates in the water… So we would definitely be able to pick those up, but sound does do strange things at the boundary between two mediums. So does light if you’ve ever seen how a straw can appear distorted in a glass of water. So you may find that much of the sound is refracted or reflected at the surface. That would also be why you can easily hear whale song under water, but not at the surface.

The way it was taught to me was by imagining the sound or light as a car. The wheels will turn at different speeds depending on the medium they trave through. So as the car approaches the water at an angle, the corner wheel that makes contact first will speed up and cause the vehicle to turn, changing the angle as it passes between mediums.

I hope some of that is right/makes sense… At least until someone explains it better 🙂

When waves hit an area of different density, they will react. Water is much more denser than air. When waves travel through air and hit water, most of it bounces away, and what’s left, the waves that actually go into the water, have very weak energy, and as the wave travels through more water, it loses a lot of energy.