It can reduce noise, mainly because the airflow is better and so the fans can be run slower. Or it may allow larger fans. But before buying a new case you may want to look at ways to quieten your current case such as 7 volting the fans or buy better quality ones, etc.
Also it's often the motherboard components which are the noisiest: the cpu fan, psu fan, chipset fan or graphics card fan. In my machine the hard drive was noisiest as it had a high pitched whine until I replaced it. So before buying a new case try to isolate exactly where the noise is coming from.