Let's say you are in a space ship.
The inside is filled with air, a medium in which sound waves can exist and travel.
Then there's a wall, still a medium in which sound waves can exist and travel.
And outside, there is a vacuum, sound waves cannot exist.
As sound waves have energy, they can't just disappear, because their energy can't just disappear.
My question is : When there is a sound in the spaceship, what happens just where the wall ends and the vacuum begins ? Where do the waves go ? Where does the energy go ?
Best Answer
Sound waves inside the ship hit the wall and are reflected but also somewhat absorbed by the wall, which makes the wall oscillate.
If there was air at the other side of the wall, the oscillating wall would cause sound waves to occur but if there a vacuum there then there's no medium to form sound waves with. So no sound can be transmitted through the wall if the other side is vacuum.
The energy of the sound waves hitting the wall is partly reflected by it, partly absorbed. The absorbed energy is gradually dissipated due to the fact that no material is 100 % elastic, so some hysteresis (friction} will always occur.