[throwmeaway33]

I remember doing the math in my undergraduate physics studies. Air molecules actually do not move very far when a vibration (ie. sounds) goes through them. Amazingly, high frequency sounds move air back and forth only a few angstroms.

I can't find a link describing the calculation. This link talks about how the change in pressure is equivalent to "140 molecules for every million molecules" http://www.silcom.com/~aludwig/musicand.htm

So there is no way you are going to create a bubble of vacuum!

[geon]

The article talks about low frequency and high amplitude. The sound waves near a subwoofer definitely moves the air more than a few ångström...

And you don't want low pressure, but high, so the air speed is low. Drag is proportional to the density, but proportional to the square of the speed.

[cma]

Not trying to create a bubble of vacuum (though that was my old idea =).. then I realized what you lost gained by low density you paid for in high velocity).

Also, the idea here isn't involving high frequency sound.

[hotpockets]

In the long wavelength regime, frequency is proportional to 1/wavelength. In fact, frequency=speed/wavelength.