I didn't hear anything unusual, but if they're BFG or Yokohama then yea they will be loud.
if you look at the tread blocks of a tire, you'll notice that they are differently sized, usually in a pattern of three changing sizes. This is to dampen harmonics.
it honestly might have been the same effect as to what this huge ass swamper tires on the trucks are having happen. depending on the "tread" of the dyno, and the tread on the tires, you might have basically heard them "slapping" together causing some excessive noise.