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Re: HUM_FORUM: Why low-frequency noise is more noticeable indoors than outdoors.

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  • Steve Kohlhase
    Steve et. al. You may find these useful to understand how ground born vibration (sound waves) interact with buildings and structures.  There are many other
    Message 1 of 3 , Mar 9, 2013
    Steve et. al.
    You may find these useful to understand how ground born vibration (sound waves) interact with buildings and structures.  There are many other references that discuss how ILF/LF surface waves along the earth can travel long distances unsensed theen interact with a structure to casue a hum/ rumble.
    PS the FTA doc from the Federal Transit Adminsitration in the US.  The other is from a great collection of relevant articles in Nosie and Health publications.
     
    From: technicanalyst <mr.steven.brown@...>
    To: humforum@yahoogroups.com
    Sent: Friday, March 8, 2013 5:17 PM
    Subject: HUM_FORUM: Why low-frequency noise is more noticeable indoors than outdoors.
     
    Basically, a building acts as an acoustic low-pass filter, allowing low-frequency noise inside while attenuating mid-frequency noise and blocking high-frequency noise. A building can also resonate to the noise, similar to a bass drum. Because the indoors environment is quiet except for the low-frequency noise, it is more noticeable than it is outdoors, where there is no resonance and sounds of many different frequencies combine to mask the low-frequency noise. A wood-frame building is practically transparent to low-frequency noise, because wood can actually flex with the sound waves, whereas the walls of a concrete building act more as a barrier to low-frequency noise. However, even a concrete building cannot stop vibrations coming up from the ground.

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