soundproofing suspended ceilings

Hello,
Does anyone have any suggestions on limiting sound transmission through suspended ceilings?
I really have two questions:
A) in a commercial setup where there is suspended ceiling in use (which means offices are just big cubicles in the building shell capped off with suspended ceiling) how do you keep noise from traveling out of a noisy room? The suspended ceiling does little to stop the noise from exiting through the ceiling and because there are no walls seperating the offices above the suspended ceiling, the noise migrates down into adjacent rooms.
B) in same scenario outlined above, if you can't stop the noise at the source can you add something to the suspended ceiling in adjacent rooms to limit migration of noise into them through the suspended ceiling?
For A) I'm wondering if I can't hang egg shell foam sheets above the walls (in plane) maybe mass loaded with carpet padding affixed to it. I don't even no how that would hold up with fire codes. I have no idea what fire codes would be like above the suspended ceiling, whether there are limitations as to what you can put above them.
For A) I'm considering rolling out insulation over top of ceiling, possibly egg shell foam properly fire rated (and I'd make sure I was allowed to do so by code). Again, I wonder if 'mass loading' with carpet padding might help? (And again, of course there's the fire code allowances to do so.
Dean
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Blow Cellulose insulation on top. of course if there's mechanical or electrical to be accessed periodically, that may not be a viable option.
steve

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dean snipped-for-privacy@hotmail.com wrote in
com:

There are several issues here. In most such office areas, the area above the suspended ceiling is used as a return air plenum, thus restricting the kinds of things that can be placed there. I'm afraid that probably the only kind of insulation allowed would be enclosed fiberglass batts. You also have the issues of requirements for open air spaces around the light fixtures.
If you have only one or two offices that need to be soundproofed you might be able to get permission to place enclosed fiberglass bats over those offices only, as long as you make allowances for return air flow from the office into the above-ceiling area, and don't cover over any light fixtures. The best thing to do would be to contact a building inspector from your local authority and ask them what would be permissible and what others may have done to accomplish the same task.
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As tim has already said, the major consideration is the routing of return air if it is a plenum return. One of the best solutions if you have a ducted return would be to extend drywall to the deck around the problem area. Additional layers drywall and addition of sound panels to the isolation wall will increase the isolation. Contact a local drywall supply house and investigate sound board - a brown cellulose sheet product that can be cut into grid sized pieces. It will double the weight of the drop ceiling, so make sure the hanger wires are adequately spaced and in good repair.
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On Jan 17, 10:11 pm, dean snipped-for-privacy@hotmail.com wrote:

How much noise is it, is it talk level or jackhammer. anything can be sound proofed but cost is determined by db level. Radioshack has db meters, then you will know what to do by a rating, db = decibel.
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