Eli5: How does sound pass through closed doors or through fabric? For example under a blanket?
In: Physics
Sound is a series of compressions and rarefactions along a medium. If it can vibrate it can transmit sound.
Sound is molecules of air vibrating. Those molecules hitting the door make the door vibrate which in turn makes the air vibrate other side, producing the same sound but muffled because the door material is not good enough to reproduce the exact same sound.
Fabric has gigantic holes compared to the molecules of air (you can easily verify this by getting a blanket between your hand and your mouth and blowing) so they have very limited effect on the path of sound.
Sound is just vibrations – the air outside vibrates the door, which vibrates the air on the inside ~|~ It’s quieter on the inside because the door absorbs some of the energy instead of passing it on
Good question! Close doors still have little open spaces that let sound vibrations pass. Now when talking about closed windows it depends on the density of the glass. I might be wrong, if so feel free to correct me!
Fabric isn’t perfectly airtight. It also can itself vibrate. The sound is a bit muffled but since it’s just vibrations that’s how it works. The doors also vibrate. Even Windows vibrate and state spying has been done by utilizing a very sensitive laser sensor aimed at the office Windows of important people that detect the minute vibrations and can use that to get audio.
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