Soundproofing Offices, Meeting Rooms and Consulting Rooms - Do's and Don'ts
Don’t use soundproofing foam - There is one thing that really doesn’t work - putting acoustic foam on the walls (or any acoustic absorption for that matter, polyester board etc). If anyone tells you it will, ask them to give you before and after acoustic isolation (transmission loss) figures, and I bet you they can’t and wont.
Don’t take advice form those not qualified - Similarly, if the friendly builder/handyman/plasterer tells you they know what to do, ask them the same thing as the foam guys and they will have no idea. Would you spend time and money on a gut feel??
Do engage an acoustic engineer - It is a complex problem that requires assessing all noise transfer paths and bringing them to a common level that is sufficient to stop the level of noise that needs to be isolated. This includes, doors and door seals, walls, ceilings, glazing, air conditioning ducts etc. For example, there is no point making a wall highly soundproof if there are drop in ceiling tiles as the sound easily travels up and over the wall.
A good overview of the common problems is here Office Soundproofing Advice