Ceiling speaker backboxes

["Benfield, John (Penta)" <john.benfield-eds@xxxxxxx>]

When installing speakers into ceilings is it worth creating some kind of
back box for them. I was thinking of this for two reasons, firstly I guess
that it could improve the sound coming out of the speaker by limiting the
amount of air space behind this speaker and secondly to try to reduce the
sound transmission to the room above. I was thinking about either making
the
boxes out of expanded sheet insulating material (such as Celotex) or a
simple plasterboard box with some rockwool/fibreglass around it.

JB