It is most certainly possible. Ridiculously expensive? Oh yes. I can't say exactly how much material you will need to drop it from 85 to 50 decibels, rather than totally silencing it, but nonetheless soundproofing materials are very expensive, as a general rule. You will basically be creating new walls over the existing walls of your structure, panel by panel. The cost is going to depend entirely on the size of your building, but you can look
here to get an idea. You'd want the larger flat panel products, not the wedge-foam things.