High-pitch tone while accelerating on Azuma

[endecotp]

I'm on an LNER Azuma and hear an unpleasant high-pitched tone whenever the train is accelerating. The frequency is constant but the volume varies.

I'm wondering if this is coming from the public address loudspeakers, picked up from the power electrics?

Is this a known issue? Does anyone with some technical knowledge happen to know at what frequency the power converters operate on these trains?


Thanks.

 

[Bletchleyite]

I notice this on all 80x on electric and I'd agree it is quite annoying. You don't however seem to get it in every coach so I guess it's a piece of electronics that isn't in all of them.