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Hearing outside noise while in an encolsed room

  1. Jan 8, 2006 #1
    The theory is that sound is heard because of fluctuations in the air molecules that surround us but why is that we can hear noise coming from outside when we are in an enclosed room? Is it the case that air molecules are able to travel through the walls of an ordinary room?
  2. jcsd
  3. Jan 8, 2006 #2
    The fluctuation is in the air pressure. These fluctuations make the windows and other solid materials, which our homes are made of, to vibrate a little. Then these vibrations create fluctuations in the air pressure inside the room, i.e. they are making sound which we can hear.
  4. Jan 8, 2006 #3


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    Yah, sound doesn't just travel through the air. It will hit any other object and send the vibrational energy through it and once it hits air again, it gets to spread to your ear.
  5. Jan 8, 2006 #4


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    If you turn up your stereo moderately loud, feel something near the speaker. Or turn it up really loud and feel the walls. Yeah, they're shaking.

    Also, the denser medium, the faster sound travels. The speed of sound in air, is slower than the speed of sound in water. The speed of sound in water is slower than the speed of sound in steel.
  6. Jan 8, 2006 #5
    So sound will make air molecules bunch up and bunch down thereby creating pressure. This oscilating pressure will eventually hit the outside wall. The wall will receive the momentum of these air molecules and pass this momentum on to the air molecules inside the room, although much less than the momentum that it received. That is why I can detect sound inside my enclosed room although at much less intensity.
  7. Jan 9, 2006 #6


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    Exactly, because the air doesn't push very hard on the wall, the wall does not transmit the sound near as loud.
  8. Jan 10, 2006 #7


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    Sound travels through just about anything but a vacuum. However some substances, like sand will dissapate sound pretty quickly.

    If you could directly attached a solid object from your ear drum to the wall, you'd definately would hear the sound. If it was a solid steel beam, there would be less dampening effect.

    You can definately hear sounds while submerged in water.
  9. Jan 10, 2006 #8
    How did you happen to know this? Does this mean loose sand or cemented? It's hard to imagine a wall of sand that wouldn't be cemented somehow that someone could test for sound deadening properties. Would sand be better than soil at dissipating sound?
  10. Jan 10, 2006 #9


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    Sand is good; snow is even better.
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