Thanks for your comments Rainboe.
I use the headphones almost exclusively in noise-cancelling mode only, certainly when anywhere near the ground. They make it easier, not more difficult, to hear conversations and announcements and surely there is no electronic or interference issue with them?
Doing as I'm told does sometimes go against the grain, but only if there isn't a good reason to do as I'm told!!
Stern looks or requests are, of course, always complied with.