Richard they do make a drywall that does have some soundproofing effectivness.
http://www.quietsolution.com/Its something to do with both the thickness and the way they blend the material between the paper face. We have used this in the past. Its very expensive stuff and really does not do that much more then the plane stuff used every day with proper sound proofing methods done.
To answer Jenyyy
No drywall or material should smell in a new home. You need to get someone who does moisture and mold testing. If this material is used as a common wall between units. There may be a leak in the wall that is occuring. Drywall of any type often smells once it gets wet or damp. If its wet for any length of time the mold that develops often is quite smelly as well.
If you contact someone who does mold and moisture testing Do not let them talk you into expensive mold testing all over the house. They can however do an in wall air test in the suspect area to determine if any mold is present within the wall cavity. But the inspector should have some experiance in doing this type of test and know how to understand the results that come back from the lab. The more important thing that is needed is moisture tests. Readings should be within the 12% range. Test readings need to be done both on known dry areas and areas that are suspect. Compare the readings to the know dry area to deterimine if there is a leak somewhere.
If they rely on the lab to determine if there is any issue based on the results do not use that company. Proper mold testing and evaluations should only be done by someone who understands how to read the reports and combines them with on site evaluations. Its not the labs responsibilty to tell you if you have a issue or not.
You can check on Service Magic or any of the many other search engines off the web to find someone who does this type of work.
If you spoke to the builder and he told you that the drywall was soundproof material. So what? Did he answer your concern? Or did he say someing like that is normal and it should go away as the house ages? He or she should be running to help you as if there is a leak it could end up costing them thousands to fix if left unchecked.
As I told many folks on this site. Trust yourself. If you think there is something wrong. Your most likely right. Regardless what the person that did the work told you.
I would also speak to your attorny that you used to close on the house with. If this is a newer home there are many warranties that are often in effect that can be voided if not handled properly.
Do not accept any repair from the builder or any other contractors until you know that there is a warranty with the work being done and that your attorny approves of this so not to effect your home warranty in effect.
