I listened to the videos of these sounds being heard all over the world. One thing that we noticed is that this is a pattern.
There are no instances of these sounds happening in my country though.

1- They sound like chorus-kind of chanting like 'Om' mantra or is it only me? If you listen closely it is very uniform with the intervals.
2- There is this movie called 'The Objective' where the people are duped by these strange sounds, lights similar to Choppers, Aerial vehicles towards the end of the film. Unknown, invisible crafts communicating, deception?
3- Sounds from other dimensions?

It's all bullcrap. I heard a noise when everyone started hearing it. It wasn't some musical instrument. People are being ridiculous with this now. I heard a loud rumble, and that's what a lot of people are hearing. This thing with the horn is b.s. C'mon on a serious note (no pun intended) let me guess angels are playing horns in the sky? Ghosts?

i haven't heard a noise. havent met anyone whose heard them. it's such a hard thing to buy into being how easily it can faked.

It's called the Waterphone, makes all the sounds that are on Youtube for "scary sounds" and such.