> I think that nice reduction and cancellation is the largest step to a better urban environment. Being able to play guitar, at proper volume, in an apartment, without hearing my neighbor's washing dishes, the cars outside, or the newly wed couple 2 windows over is a fantasy. A fantasy that engineers and architects might be able to make real.

I agree. I don't know how much money or effort that goes into this kind of thing, but it seems like the absolutely most bang-for-your-buck investment if you want to create more liveable city apartments.