The "Hum" In Central Texas - Cedar Park and Round Rock

Another report of the strange and annoying “hum” has come in, this time from Cedar Park, Texas.

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We live in Cedar Park, which is not far from Round Rock, TX. I have been hearing a low rumbling, noise that sounds very much like the noises that are being heard in Round Rock, TX. I have asked my Mother many times, if she hears it, and she sometimes does and sometimes doesn’t. It is always late at night between 11:00-2:00 when I hear it. I cannot pinpoint the exact area it is coming from because it seems to emanate from below the ground or in the sky. It is loud, constant and luckily I don’t hear it in my bedroom, which is on the North side of the house (I hear the noises only outside on the South side of the house). I sure would like to know what is making these noises, if you find out please let us know.
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As I stated in my previous report [Strange Sounds and Vibrations In Round Rock], these sounds seem to be heard by only a select few, apparently by people who are sensitive to low frequency sound waves.  
Sounds can travel through gases (air), liquids (oceans), and solids (Earth).  To learn more, read How Sound Travels,
Could these sounds and vibrations be due to mere highway noise?   The cause of this phenomena is yet unknown.  Let’s work together and find out!  -Sunny

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