[Scott Dorsey]

HiC wrote:

The refrigerator being on or not doesn't seem to make any difference,
it's 2 rooms away - the sound would have to go through 2 walls plus
the sound booth wall which is built exactly the same way as the house
walls.

It doesn't go through the walls... it vibrates the floor, then the floor
under the mikes vibrate. Low frequency sound is VERY readily conducted
through the building structure. That's much of what makes commercial
studio rooms so expensive to build.studio rooms so expensive to build.
You may not even hear it, but put your fingers out and lightly rest them
on a tabletop and see what you can feel.

Good shockmounting can reduce the problem, but it won't eliminate it.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."