Strange noise on Greater Anglia Mk3

[Bungle965]

Hello
Recently I traveled on a GA Mk3, and about 5 minutes into the journey a very loud noise came from the speaks (which can be heard in from my attachment). I was curious as to if anybody would be able to tell me what this strange noise was. The guard did not seem aware of it as he was making a announcement at the same time as this noise went off. In addition the carriage had no electric maybe that has something to do with it?
Any help would be appreciated.
Thanks
Sam

 

[dk1]

It's just the disabled alarm in coach J. Either in toilet or wheelchair space. Usually reset by the adjacent catering crew member.

 

[Bungle965]

It's just the disabled alarm in coach J. Either in toilet or wheelchair space. Usually reset by the adjacent catering crew member.

That was one of the things that crossed my mind.
Thanks for the quick reply.
Sam

 

[dk1]

That was one of the things that crossed my mind.
Thanks for the quick reply.
Sam

My pleasure. If it's a trolley only set it can take a while to reset if the senior conductor is in the DVT. The reset is in the cupboard next to the disabled wc. It is not connected to the train brake or driver in the way the pass-com is.

 

[Crossover]

Thanks dk1! It was flipping loud - glad we only had to put up with it for a few mins before we arrived into Liverpool St. However, I am a fan of coaches without working lights