The human ear, due to it's shape, adds subtle filtering to sounds.  Things will sound marginally different if heard from in front or behind you. The size and shape of your head, and the fact it physically blocks one ear from the other, does a similar thing to the left|right field while also inducing extra phase differences as well as volume differences.
 
You won't be able to consciously notice any of these subtle changes because that is how you normally hear things, but all these things put together mean our brain can calculate in 3D space where sounds have come from,  not just in the left|right stereo field our two ears would imply.
 
The "head" tries to replicate this with mics in its "ears" to record what a person would hear from that point in space.  When played back through headphones you should get a true 3D sound field.

craigb
Or just a headache, ya? 

Most likely,  yes.

batsbrew
so,
my question is,
 
what does neumann do with this setup, that is different than, say, a typical X-Y setup?
how does it differ?
 
 
and if i wanted central imaging, why would this be better than, say, MS?
 

X-Y would be at right angles from each other, the head would be basically 180 degrees more or less.
 
I think it would give a totally different perspective than x-y.

Karyn
X-Y could be seen as the raw, unfiltered sound, while the "head" adds the filtering we have naturally with our ears.
 
It works best with, and was originally designed for, headphones.   If you listen through speakers, it will definitely sound different, but you'll be doubling up the effect by default simply because you're listening with your own version of "head".  That does not mean it is twice as good...  it could just cancel the effect, or even over exaggerate the effect.

So, basically you're saying that two heads are NOT better than one? 

aha,
 
head-related transfer function (HRTF)

batsbrew
well, the ears curve forward, so it is not exactly a 180 degree relationship....
but couldn't a simple screen between the two mics provide the same level of cancellation as the plastic head?
 
the mics that are sunk into the head, surely are not capable of the same frequency response patterns as a mic on a stand?
 

Right, and I said "give or take" meaning not exactly 180.
 
but it's far from 90!

LOL