I think a couple resonable possibilities are as follows:

1) The "noise" is coming from our own galaxy. This may have something to do with our current positioning in the galaxy, which is more or less at the equator. Perhaps at this point there is some kind of a reverberation or inlet to our solar system of this commotion taking place in our galaxy's magnetics or from the distant universe.

2) Another possible scenario I think may be that our universe is not nearly as uniform as they think. As stated in the article, "The only way this noise could be made from the stars and galaxies is if they were packed in like sardines." This may suggest that the space in the universe, what they think may be dark matter or a vacuum, is something else entirely, perhaps in a way an illusion or something. (by illusion i just mean something other than what it appears to be) allowing for what we see now as the noise from all the galaxies being packed like sardines to actually be the case, in a weird sense that would alter space sciences and physics completely.

Just some random conclusions i came to earlier after reading this article.

Nice find! Wish they would give a sound bite of the noise. Will be following this. S&F.