could you be more specific!
Must be a heck of a Synthesizer to be heard that far around?

http://www.ryot.org/weird-trumpet-sounds-coming-sky-freaking-people-across-the-sky/935404

I have learned never to trust internet "marvels," so I don't trust these AS PRESENTED, either.

However, sounds similar to that could be produced by wind blowing over the right kind of construction in progress.

Ever play a game with a plastic tube when you were a kid? We used to find these plastic tubes that were made in a ribbed manner, so that they could be stretched out as needed. We discovered that if you grab one and swing it rapidly around in a circle, that the air moving across the end of the tube, would sound like a horn, similar to the sound you get if you blow across the top of a beer bottle.

If someone were constructing tall metal exhaust stacks for a new apartment building, and wind came up from the right direction, the stacks might sound like some of those recordings.

But as I said, I've run into too many hoaxes where people added their own recorded sounds over the actual sounds, in order to make the people trying to figure whatever was ACTUALLY being heard out, appear to be responding to what the hoaxers played on their synthesizers, or made with old tubes and blowers.

the "trumpet sounds" have been around for a while, they are referenced in the bible a few times... personally, i think it's the sounds of the earths magnetic field lines twisting/bending...