I understand how sound waves work and how humans perceive sound. I don’t understand how a persons speaking normally has enough to power to vibrate something as solid as a wall to the point that we may even discern what someone is saying.
In: Physics
In a still bathtub, drop a single drop of water….. see how the ripples keep going? A single drop of water doesn’t seem like much energy, but it’s enough to displace all the water around it when it falls…. Then all that displaced water moves the water next to it just a little bit at a time until a ripple covers much of the surface.
This has more to do with the remarkable sensitivity range of our ears than the power of our voice. No matter how weak a sound it *will* move walls a bit. A normal conversation is something like 60 decibels, while 0 decibels is considered the quietest a person can hear. This means that we speak at a volume 1000000 times louder than the quietest thing we can hear. If there’s no other background noise to cover up the quiet voices, that leaves a lot of wiggle room for how muffled a sound can be by the wall while still
being heard.
This is largely about how thin walls are. You can’t really talk through a brick wall, but interior walls are often made of thin, vibratable stuff like wallboard or plaster. And part of exterior walls is glass (windows), also easy to vibrate.
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