What do you think when two people whisper while another person is present? If I genuinely needed to whisper something, I would still be aware that another person present would wonder if I was saying something about them... and therefore I would not do it. In fact the last time I came across this I'm pretty sure the person whispering was trying to piss me off. Therefore the person being whispered to would have been being used for this purpose.
I met these two women at a house party last year August '19 They whispered in front of me and then again looking at me from across the room whispering with lots of sultry eye contact. The night ended phenomenal. Both these ladies are still in my life and date them periodically. I don't consider whispering rude. It's a green light to approach, meet and convo.
a lot less rude then when people rob each other of thinking their own thoughts by trying to see how much loud and disturbing they can be. if people don't want me to be part of their trip, that's ok, but i sure don't need them to be part of mine.
Silence is golden. It is to be preferred over someone talking loudly in their cellphone or lunch room.