I have set up a recording booth behind my control room. It's a bit makeshift at the moment (though very usable), & not that greatly isolated from the outside world, particularly through one side wall. I put in several panels from my old studio to deaden the room a bit (nothing fancy, basically old office partitions with foam & fabric attached - basically gobos). The room still had an unpleasant ring to it, which I determined to be from the ceiling (to floor). So, using what I had, I strung up a sheet of 100mm (4") Tontine Acoustisorb insulation, which runs the full length of the room & 1/3 to 1/2 the width & sits about 1" away from the ceiling. This got rid of the ring, & made the room sound quite suitable for recording.
Once I put the tontine up I noticed that noise from the outside world was greatly reduced, quite a dramatic difference in fact, even though this treatment was not on the side wall most prone to leakage from outside (& it was not even covering the entire ceiling). I'm guessing that the tontine is soaking up reflections which otherwise seem to amplify the outside sound? Interesting, & very helpful!
