For those interested in the various aircraft systems for PA (public address) and aircraft status system for aircrew, I found this interesting training doc PDF online [1] for the A320/321. I have been looking at section "03-010 CABIN INTERCOMMUNICATION DATA SYSTEM" It does not mention the "medical intercom jacks" in overhead bins that are mentioned at the end of the article [1]: https://caisatech.net/uploads/XXI_3_AIR…
Apparently there is a compact flash card to play music and the pre-recorded announcement over the loud speakers. I wonder if someone replaced the standard announcement with a 5 hour long file with intermittent burps and groans....
Another idea is that there is a source file that is copied onto the flash card on a regular basis and someone has hacked the source back at the office or something. Seems more likely because that wouldn't require the perpetrator to be on each flight and thus less likely to get caught. Some of these flights play music as you board the plane, could it be that this comes from music on a flash card and someone has replaced that?