Was there an AM transmission station nearby? Sometimes some metal objects can act as an antenna-speaker combo when there's a high power AM transmitter nearby. (some people have even reported this happening with dental fillings!) I'm assuming this is a bell or some other low-tech thing, if not there are probably many other explanations
This gives me an idea of an attack vector. These groans and moans seem rather quiet, and the airline claims its an amplifier issue. Assuming that the amplifier is not shielded from the cabin and that its analog tech, one could theoretically induce intentional interference to play whatever you want, right?
Not to my knowledge, but it's possible. There certainly wasn't a radio tower around, but there were antennae all over the place, as there are on any large campus. I don't think that's what was happening; it seemed to be different alarms at different times, but I believe it was always the same song. Which seems to me like they were being randomly selected by a script. These were fancy fire alarms and it was 2014, it's entirely plausible in my mind that they were networked and running a vulnerable embedded Linux. I don't think it'd be a Mission Impossible level effort to make this happen.
But, I'm going off of 8 year old memories, so the only thing I can say for certain is that it happened.
