Physics of downward firing woofers


Ok ... this question will show my complete lack of knowledge about physics ... but here goes anyway:

Every now and then I come across a speaker with a downward firing woofer. I wonder: why don't the sound waves bounce off the floor back towards the speaker, rattling the bejeezez out of it and / or messing up the woofer itself?

~Jim
128x128jimspov
Ralph, did you remove the carpet to compare or move everything to identical room ?
As you know I have a set and have shown with them at shows since the early 1990s.

I've had carpet underneath mine and also bare wood floors (went from wall to wall to tribal rugs about 10 years ago). At shows we've often had carpet and it seems like other factors of hotel rooms are issues- usually we are trying to tame the highs in the room. Things like false walls and false ceilings are far more problematic for bass. Such things act like bass traps but usually you don't run into problems like that at home.
Sound travels at about 1087 ft/second so the length of a 40 hz bass wave in 1087/40=27 feet.  Carpeting won't have any significant effect on a wave that long.  It's why bass traps have to be so big. 
The Vandersteen 2Wq sub has 3 eight inch woofers facing downward at the bottom of the cabinet with no holes for woofer exposer. It seems to have slots cut around the bottom outer edges of the cabinet where sound comes out from the back side of the internal woofers. All you have to do is listen to these subs properly setup and make your own decision as to how they sound.
I have 2 REL's and have wondered if carpet, or a pad under the drivers is better for sound (to reduce relection) or not. I have not expermented with it yet to see. Any thoughts?