HUMMING SOUND heard across New Zealand capital last night

Not sure if this was posted already but i woke to the radio this morning and they were all talking about a humming sound heard across Wellington city last night, heard widespread, and they had a recording, very eerie sound. You can probably go to THE ROCK radio station and hearthe sample.

I noticed haarp activity is high i wonder if its connected or if its just the aliens sayin hey man whats up :)