Today I did a choir concert in the local community college auditorium. I used an ORTF setup with two RODE NT-2A microphones. I was back about 20 feet from the first row of the choir and up about 3 feet over heads of the singers in the back row. Pretty normal setup for us. The problem is the auditorium, which if you look at its floor plan is a big Mickey Mouse, with the two ears that can be rotated to other venues located behind the main concert hall. The stage is enclosed by a shell and the ceiling for the shell is dropped from the stage house. It is basically a shell with in the stage. Any way our problem with that we were getting bounce off something which made the main sound image seem to swing back and forth between the center and left right. I can fix it but this was strange. Our hosts and the people on the stage crew were great and they made my job very easy and it is one venue I like to do because of the stage people and their can do attitude. Has anyone else run into this problem?