Strange noises from the sky

a couple of months ago, around 3 or 4 pm-ish, i heard a strange rumbling/plane-like (i cant really explain) noise coming from the sky. i was in my room at that time, at first i thought it was a plane but it kept on going, with the same volume. (you know how sometime planes sound fades away) so i was like, what the hell is that, and i opened my curtain to check and there was nothing, at all. not any wind, no nothing. it doesnt sound like thunder at all, a weird thunder maybe, but it was a sunny day. i freaked out, and it kept going and i kept searching where it came from, but couldnt find it. it stopped for a while but the went on again. so i checked my blackberry (coz people ususally make status when something weird happen) and no one seem to realized. so i thought it was only me, or it was something i couldnt explain. altho a couple hours later i saw 1, just ONE, of my friend updated a status that said 'what was that noise?' but i thought maybe its a different noise. anyway, i ignored it. it only happened to me once, i never talk about it to anyone, i never think about it, i just thought it was some construction or something, and it has been 2 months/more and i JUST found out like hours ago, that there are videos on youtube where they recorded these weird noises from the sky. The EXACT same noise i heard months ago. i went pale. Some side of me feel relieve that im not the only one, but at the same time creeped out.
so, since i figured that i am not the only one, is there any explanation to this? i've been searching but i cant find any legit answer.

There are people all over the world that are reporting this noise. I don't know what it is but take a look at something called HAARP Weaponry on youtube. I think it has something to do with that.

I am doing research for this the last time and all I can come up with is that this is something paranormal, because there are many recordings in which you can just hear a clear trumpet sound or booms in a pattern. so theres weird stuff going on. I guess we must wait f there's really about to happen something.

Well, there were these scraping sounding noises across the globe a while ago coming from the sky, they called them the "Mayan Horn", but who knows. It could be some construction, it could be something paranormal...

Maybe a neighbour was using the lawnmower to cut their grass.

Ashley - a lawn mower? really? I'm sure the asker would be able to tell if it was a lawn mower...

it must be ALIENS OR a non cloud THUNDER