foam that would harden actually would not reduce noise significantly.
Also, a "pumped-in" type of installation is
likely to collapse the chute. It's very tricky to control the amount of
expansion of foam products.

If you can make access holes through the drywall, it might be possible to
fill the gap with a rockwool type of insulation.
provided that there is a firebreak installed at the floorline that will
retain the insulation.

Anything you would do external to that existing drywall, though, should
probably be cleared through the condo
assoc or whatever. You could get into some deep dudu ($$$) if something
went wrong.
bill

wrote in message
oups.com...
I think it will be tricky to build any internal (to the condo)
solutions. The chute and room span the bedroom and the bathroom and a
dividing wall between the two. There has to be something I can put
between my wall and the chute to deaden the noise at least a little.
What about pumping foam or something in? Would that help?