playing subs on a loop question

[RubbeR]

PS Someone with more sound-engineering skills would have to confirm this, but I believe higher frequencies travel shorter distances. In other words, US will not travel as well into the next room compared to a masked track.

Higher frequencies get " blocked" by obstacles easier, therefore they will also drop in dB faster with increased distance to the source. So if you go into another room, keep the door open. If there is multiple rooms/doors between you and the source, you probably wont hear the US.