Light is a pretty short wavelength and it cannot pass through walls but 
x-rays can, THz waves can but UHF, VHF HF and LF cannot.  Audio cannot pass 
through walls.  Audio waves are mechanical and can cause the wall to vibrate 
at the same frequencies and thereby vibrate the air molecules on the other 
side, which re-creates the sound.  It may seem as though the sound goes 
through the wall but it does not.  The mechanical force of the vibrating air 
molecules cause the motion of the wall.

----- Original Message ----- 
From: "Cedric Chang" <cc@nope9.com>
To: "Microcontroller discussion list - Public." <piclist@mit.edu>
Sent: Wednesday, June 27, 2007 4:10 PM
Subject: Re: [OT] Why do I only hear the bass drum?


> Okay, I am think I am the only substantially correct answer so far.
> It has to do with wavelength.
> Shorter wavelengths have trouble bending around objects and have
> more difficulty passing through objects ( like walls ).
> Longer wavelengths not only bend around larger objects and
> pass through walls more easily ; they are more likely to cause
> objects to resonate which creates more ugly sound.
>
> Imagine a car next to you with the bass turned up.  The car seems to
> actually move up and down with the bass.  No matter how high an
> amplitude the higher frequencies attain, they don't move the car
> although they may shatter a goblet inside.
>
> Cedric
>
> On Jun 27, 2007, at 12:31 PM, Lindy Mayfield wrote:
>
> It doesn't happen often, but now and again a neighbor some houses
> down has a party or for some reason turns up the music really loud.
> And it's the worse possible music to pick because it has a very loud
> bass drum on every beat.  Probably techno.  So all I hear is boom-
> boom-boom-boom,boom-boom-boom-boom,etc.
>
> It's worse than Chinese water torture.
>
> Anyway I was trying to understand why I only hear the bass.  Is it
> because of the length of the wave that it travels farther or through
> more things than the higher notes?  I was trying to make a comparison
> for example between AM radio waves, FM, and cell phones in the
> gigahertz range.  Or is it because there is so much more energy in
> the bass?  But then I though how far away one can hear a mosquito
> with a high pitch in a room or how far a piccolo or fife will carry.
>
> Does anyone have a theory or answer as to why the bass carries so
> far?  At least thinking about the physics keeps me from going
> postal.  (-:
>
> Lindy
>
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