[droolmaster0]

ok - so, you seem to be saying that there is every possibility that, even at low volumes, and the speakers on stands (on a rug), the low frequency energy is still being transmitted through the floor to the wall...

But cement blocks should help?

Originally Posted by xaMdaM

There's little point in trying to explain the physics to you in a forum where it's improper to quote copyrighted material. I'm not a physicist or mathematician, so it's a bit tough for me to cleanly explain all this without posting protected publications.

I would suggest getting a copy of any number of books at your local university's library on the physics of music and studio construction, if you really want to understand the why's and how's of flanking, isolation and sound proofing. I would suggest Rod's Gervais' book; "Build It Like the Pro's", Alton Everest's book; "Master Handbook of Acoustics", Beranek's; "Physics of Music", and Philip Newell's; "Recording Studio Design".

Most of it IS counter intuitive in what you would think is a logical approach to understanding and dealing with the physics of sound... ESPECIALLY, low frequency energy.

I will leave this thread with one last attempt to clarify what you are dealing with... When you walk across a floor, knock on a door, open or shut a door to a room, drive a nail in a wall, play music or run water in a tub, you are generating sound energy. ANY and ALL of that energy gets radiated in the air AND into the physical structure. Period.

ANYTHING that is physically attached to that structure will transmit that energy from itself to that attached structure. (including the air column in that structure) This is simple wave propagation.

The amount of energy that is transferred is inversely proportional to the square of the distance, for any single given frequency. So, you would think that after a couple of feet, the energy will dissipate from absorption.

However, this is complicated by the fact that there are multiple paths for the energy to travel, even from a single source, and "musical" low frequency wavelengths can be as long as 64 feet (and longer) to complete an individual cycle. So for low frequencies, many physical "barriers" in a structure are just a hole for those frequencies to flow through.

It is further complicated by the fact that individual components in a structure have their own resonant frequencies... which may actually help or hurt the energy transfer of the wave propagation.

So, while you may not hear low frequencies in your room, someone 64 feet away may be hearing it in all it's glory. (boom box subs in a car driving down the street)

There are some things that are better left to the experts, and maybe this is one thread better left to Andre's and Rod's (and obviously some of the other folks here) expertise to try to explain to you.