cavity wall insulation

[12 promises]

can having cavity wall insulation installed change the sound of a system?

[spooney]

It won't definitely change the sound of the system , only if you change a component in your system.
What are you looking for? Getting rid of some vibrations, reflections?

[12 promises]

yes,i see the point you made

what i should have asked was will it change the room accoustics?

[clockworks]

It will change the acoustics (everything does), but the changes will likely be too small to hear.

[mattym]

Originally Posted by 12 promises

yes,i see the point you made

what i should have asked was will it change the room accoustics?

it will only change the room acoustics if you have a low quality plasterboard stud wall, if its brick, then it wont make a difference. If your wall is a plasterboard stud it could resonate at a frequency that interferes with the goings on in the room, leaving a big percieved hole in your bass, if the wall is brick it wont resonate at a high enough frequency to notice(high enough is relative here, im talking about 40hz kind of area).

If you want to make some panels to go on the wall to change the acoustics then thats easy, rockwool in frames, fabric covered carefully placed will do it

[spooney]

Originally Posted by 12 promises

yes,i see the point you made

what i should have asked was will it change the room accoustics?

It will dampen the sound in a certain frequency range to the outside world and if you stuff it tight into the free space it will lower the vibrations of certain frequencies (self-resonance of the board) a bit.
Don't exepect a big difference unless you add mass (e.g. a second layer seamless fixed to the first) or change the sound reflections properties of the wall (e.g. ingrain wall paper)