[steven]

About insulation, I'm surprised that for as "Eco" as Japan is trying to be they don't seem to put much focus on insulation. When I was looking at houses they were selling different types of insulaton from fluffy fiberglass to what was basically glorified styrofoam panels. The sellers were talking about it like it was new. The same thing goes for dual paned windows.

Upon doing some research on insulation a little over a year ago, I came across a rigid fiberglass seller nearby and got a ton for fairly cheap. I used it for sound absorption (not for my apartment). Not only does it work well for sound, but it keeps the room cooler in the summer and warmer in the winter.

Styrofoam alone aparrently reacts to sound (with reverberation and such) which is not something desirable for noise reduction. Fluffy fiberglass doesn't do much as far as low-range sound goes.

Despite the fact that I found a seller of the material, I didn't seem to find any companies who implemented it in their designs.

On a similar note, which you might find interesting (dogsbody70) is that tatami mats are actually really good sound absorbers. If anyone on here has taken all the tatami out of a tatami room (like for cleaning) you know what I mean. The room can sound like the grand canyon (all echo-ee) without the tatami in it even though it was fairly dead (in a good way) with it inside. I found out that it's particularly good for mid-low range sound but actually does reflect some higher range sounds due to its semi-hard surface (but it won't reflect like hardwood will). Not only that, but you can jump on it without having things in the immediate area rattle around. I suspect tatami is a very old form of insulation... and insulation usually means good sound absorption. In other words, I think there is a connection with some Japanese instruments (like the koto and shamisen etc) and tatami mats even if to a small degree.