system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How exactly does sound travel through walls?

Or any other solid, for that matter?
gpt
Sound is merely pressure waves of molecules bumping into other molecules, transferring energy. When the wave hits a solid object, some of the energy is transferred to the wall, allowing the sound to propagate through it. Then the molecules making up the wall push on the air molecules of the other side, allowing you to hear through the wall. Some energy is lost or reflected in the transitions, thus why the sound is muffled. And some frequencies transition better than others.