Where does sound go after we can no longer hear it?



Where does sound go after we can no longer hear it?

In: Physics

The energy of the sound wave is dispersed through the air. With each unit of distance it travels, it has to vibrate a larger amount of air with the same amount of energy (the inverse square root law) . At some point, the wave is so weak that it is indistinguishable from the background noise.

Toss a pebble in a calm pond and watch what happens to the ripples over time. Sound’s a lot like that.

First you hear it as the ripples pass you. Then, if you’re close enough to a fairly straight shore, you might hear it again as the ripples bounce back and pass under you a second time – this is an echo.

Eventually the ripples spread out from each other so far that you can’t see them (or in the case of sound, hear them). This can happen a lot faster if there’s a slight breeze that’s riffling the water, which is why background noise like the leaves on trees blowing in the wind makes it harder to hear distant sounds.