At the University of Denver’s Boettcher Center Auditorium we have finished installing the insulation in the sound wall between classrooms B and C. It is essential that these two classrooms are sonically independent from each other for the convenience of the professors and students. An STC rating of 60 is typical in this kind of situation, and because using cmu was too costly, we are achieving the rating with a metal stud wall partition. The key is getting a physical separation between the layers of sheathing on either side of the wall to isolate the vibrations. In our case our wall cavity includes two layers of metal studs, one of which serves as a plumbing chase for a new drain line.
In the photo you can see the 8″ metal stud wall (which is packed with R-19 batt insulation) that spans from the stage level up to the existing roof deck and which will eventually be sealed in with a layer of 5/8″ gypsum board. On the other side, a 6″ metal stud wall with two layers of gypsum board on horizontal isolation channels is separated from the 8″ metal studs by a 2″ air gap.