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B Question about the physics of sound

  1. May 5, 2018 #1
    Hello there! I have a couple of questions regarding the physics of sound (they may seem odd and concerning, but aren't for any malicious purposes, I promise, these questions just popped up in my head )

    First, I'd like to understand how soundprofing works, the science behind it and how well can you soundproof an natatorium. Per say, in a school...if someone were in the natatorium listening to music would it really be possible for it not to be heard in the hallways, or at least in any of the rooms near it with soundproofing? If so, I'd like to learn how (don't worry about boring me, be as detailed as you like!)

    Secondly, if someone were to put dust behind the speaker grill of a radio or any other device that emits sound, how loud would the sound emitted by the device need to be in order for it to blow it all out (or at least some of it)?

    I appreciate the help? (Sorry for wasting your time)
  2. jcsd
  3. May 5, 2018 #2


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    Hi and welcome to PF.
    Sound proofing is a difficult (expensive) business and the only really good solution involves really thick walls with no (not even a mouse hole) holes in it. This requires the structure to be made that way when it's built. Nothing else can work as well as that. If youGoogle "Soundproofing a room', you will get loads of adverts but you will get useful advice sandwiched in between the ads. This link discusses soundproofing methods (note, all techniques work both ways) and you'll see that the way for you to go is probably Absorbent Panels.
    There is a potential problem with a DIY approach and that is the risk of a narrow band of sound getting through. This can be more annoying than the full spectrum when low level tinkling 'drainpipe' sounds get out into the rest of the building. A 'professional' service would probably ensure that is avoided.
    The thing to do is read read read abut the topic and expect it to cost a lot.
  4. May 5, 2018 #3
    Bass usually if its music, nothing more annoying than hearing the muffled groaning of a wuffer and not much else when you are trying to sleep
  5. May 5, 2018 #4

    Alright...what about the second question?
  6. May 5, 2018 #5
    And also...from what I understood, sound proofing a whole natatorium is indeed possible?
  7. May 5, 2018 #6


    Staff: Mentor

    Good questions.

    Here is a video that demonstrates that. But the question "how loud" depends on "how fine grained is the dust" so there is no single answer.

  8. May 5, 2018 #7


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    I would need to be shown evidence for me to believe that. It would all depend on just how soundproof it needs to be. Heavy doors with felt seals could make a lot of difference. If the auditorium has large 'picture' windows, looking onto a corridor , that could be problematical and the windows would need to be triple glazed with a large gap.
    Basically, an ordinary building with walls of standard mass would represent an expensive project if you wanted a high spec proofing. How much money are you prepared to spend?
    The dust and loudspeaker question is also hard to answer. There is a lot of air movement with a sub-woofer and that could cause dust to be blown out.
    P.S Don't try that demo with sand on a loudspeaker cone if you ever want to use the speaker for music listening. Once you get a tiny bit of grit in between the voice coil and the magnet, you will always hear it and the speaker is, to all intents and purposes, dead. (Except for repeating the demo.)
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