Agreed with the previous respondents. Sound transmission can be mitigated regardless of construction type. Ideally, you find a building with a concrete floor structure. Most buildings over five stories in Chicago are constructed this way.
First and foremost, noise can result from many things. I'll address some of the most common noise sources here.
1. Footsteps above you: Ideally, if this bothers you too much, find a top floor. Other solutions include filling the truss (new constrution) or joist (old construction, rehab) space with sound deadening insulation. I would recommend a blow in product such as Nu Wool. It can be installed without removing the ceiling. This will mitigate the sound, but will not completely eliminate it. Wood floor creaks from a unit upstairs will often still transmit. If you purchase prior to drywall, you have an extreme and expensive, but effective option, Quietrock. This material, used in place of drywall, has various sound deadening layers and is used for sound studio isolation. You should also insulate with a high density insulation to fill the voids between joist. In concrete floored buildings (sometimes referred to as spancrete), a common problem is the lack of cork or foam underlayment between the concrete structural floor and a hardwood or tile surface. This can be difficult to remedy as the problem is not in your unit and requires removal and reinstallation of the finished floor above you.
2. Plumbing Noise: Plumbing noise is unique to new construction. Modern PVC drain plumbing has a very hollow sound when water rushes through. You may hear this when your standing under or near another units bathroom or kitchen. Owens Corning makes a product to deal specifically with this type of noise. It is installed in all plumbing bays prior to drywall.
3. Human Causes: Stereos, Parties, etc. A vinyl sound barrier called SoundStop by Celotex can be installed to isolate rooms within your own unit. Typically, Chicago calls for Masonry or Firewalls between individual residential units. Transmission through either in adjacent units would be hard to imagine. Transmission of sound between your bedroom and an adjacent kitchen would be more likely. If your creating a media room, library, or bedroom adjacent to a living area, this is a great product to have installed.
4. Doors and Windows: Hollow core doors do very little to stop sound, and can easily be replaced with solid core doors. Windows over a busy street can transmit sound. Unfortunately, replacing windows in a condo building can be a fair bit more complicated. Modern windows are dual glazed. They either have a vacuum or inert gas between the panes. This does a great job of insulating street noise.
Hope this helps, but noise is one of many reasons I bought a single family house on an oversized lot!
Here's the deal - new or newer construction condos in North Center have frame trussing into which developers blow in insulation. What this does is mitigate sound transmission between floors. What matters is whether the building is comprised of brick exterior or split faced block. Brick is superior to block. Bear in mind this mitigates but does not deaden sound transmission. One way around this is to seek the installation of cork underlay between the subfloor and hardwood flooring. Another consideration is whether the developer has installed "j" or "z" channels that somewhat subdue sound a bit more. Concrete underlay is not a common feature in three to six or eight unit condo buildings. This not so common concrete serves to reduce sound more than simple blown in insulation. Having said all of this - if you are after silence and you will feel perpetually on edge if you don't have absolute silence you may do well to reconsider the condo purchase. I also heartily endorse that you seek an experienced real estate professional to guide you through this process.
All the best,
The Real Estate Lounge Chicago
I got into the real estate industry a few years ago after spending a couple years in property management and quite a few years in residential construction. There are a lot of very good developers out there that take great care in noise reduction, but there are a lot of bad ones that are taking short cuts on their projects as well. Concrete construction is going to be the most resilient when it comes to noise, but new technologies in acoustic insulation and floor systems have made framed residences very quiet, if used right. Absolutely research any developer you are considering buying from. If you cant find anything on them, your agent should have the resources to get information for you. If it is new construction, take a tour of the units that are not yet completed and check out the construction techniques. If something doesn't look right, it probably isn't. Don't be afraid to ask questions about the materials being used and how they are applied as if you personally hired the contractor to build your home. Oh, and if you are considering anything that is not on the top floor, have someone walk and jump around the unit above with high-heels on. There are so many products and techniques out there that it is hard to be specific as to what to look for. The best thing to do is spend some time doing research and make it very clear to your agent that noise is a major concern. There is enough property out there that your agent should be able to weed through and point you in the right direction.
We highly recommend soundproof.com, they specialise in noise and sound proof with many different techniques. It depends if they are "sound proofing" the walls, doors etc. Hope this helps, give them a call or go to their web site.