Hello Swan Specialist, greetings from Denmark!

I feed two swans on a daily basis and this summer was rewarded with five cygnets - Now larger than their parents!
I have a questing regarding "swan greetings". I have observed them greeting each other when they meet, but sometimes two of the cygnets act as they greet me, when I come to feed them. Is this possble? And would a swan recognise my voice? The male acts like he understand me calling him by name(!), but am I just wishing?!?
Might be silly questions, but I have no idea who to ask!

Thanks in advance,
Anette