French Doors

I'm not a home builder but I have removed walls for remodeling. Don't remember any insulation between the drywall on inner walls which is what I expect we're talking about here.

Some do some don't Timrhu, all my interior walls have insulation for sound deadening. If there's no insulation then yes, it probably wouldn't make a difference what kind of door is used.

Tpreaves,

"all my interior walls have insulation for sound deadening"

This is a very nice feature you have but typically you will not see insulation in interior walls unless a consumer specifically requests it when the structure is built (in my geographical area anyway). Commercial applications differ, such as condo's, townhouses, hotels, etc.

We just added false walls on a duplex. The noise to/from the attached house was tremendous. It worked amazingly well. Very simple 2 day job and you would never be able to tell that it was done at all. We just lost 6 inches of space. 1 inch air gap, 4 inch framed wall with insulation and 1/2 inch drywall on each side. gave us a chance to upgrade the wiring too. Cost was minimal.

On an inside wall, packing 6" of insulation in a 2" by 4" stud wall makes a good difference too. Double the 1/2" or 5/8" sheetrock helps a lot. The wall has a thud type of sound (knocking on it), instead of that hollow sound. It's not the best, but works wonders vs. standard, and fairly cheap. They have a sheetrock that is made for this (sound dampening), but I can't remember the name or never heard it work. It might be QuietRock. [http://www.quietrock.com/drywall.html]