On 2/10/2014 9:32 PM, -MIKE- wrote:
On 2/10/14, 4:18 PM, Mike Marlow wrote:
Jeff Thies wrote:


Density matters for a lot of reasons, not the least is sound
transmission. It also adds to thermal mass. I have floating
counter top (no underneath support) hanging off a plaster lath
wall, would of been much harder to do with sheetrock.

As for sound transmission - that's not quite as simple as one might
think. Denser/harder materials will transmit sound through them
and/or reflect sound off of them more so than less dense materials.
This is not a cut and dried sort of discussion that can easily be
expressed at one being better than the other. It's probably safe
though to say that a less dense material will absorb and reduce sound
much better than a more dense material. Look at the insides of a
sound studio.


Those softer materials are there to control the sound within the room,
and do virtually nothing to stop it from transferring to another room.
While you are correct that mass, alone, doesn't stop sound from
transferring to another room, uncoupled mass does. That's why in those
recording studios you see two walls separated by an air space between
two rooms. They call it and "room-within-a-room."

Exactly!

A large mass can actually amplify some resonant frequencies to another
room. When you have two heavy masses of different resonant frequencies,
unconnected physically, virtually no sound transference will take place.
Once cheap and effective way to accomplish this is to have a cement
block wall on one side and a stud and sheetrock wall on the other.
Almost all the sound that escapes through that type of contruction does
so through air gaps in the doors, windows, and utility cavities.

Despite what the Pink Panther would lead you to believe, those rolls of
insulation inside the walls do very little for *real* soundproofing.

I agree.


Did some broadcast and recording work in the distant past.