there are several ways of communicating via Alexa
1)make an announcement - this is useful if you'vegot more than 1 alexa. I made an announcement this morning via my nearest alexa that it was time to get up, and she announced to my husband and daughter in their respective bedrooms my message. I'm not sure if you can do it to a device in someone elses house. It just broadcasts only
2)drop in - opens a channel between 2 alexa devices, either in your house or another house. It's like a 2 way baby monitor - they can hear (see if you both have an echo show) you and you can hear them. I could drop in to my parents living room, and they probably wouldn't know. I don't want to do that, as it means they could drop into me or my bedroom at any time and as you have discovered it's not a particularly loud notification so I could be doing something/saying something I don't want others to hear. You can turn this off
3)make a call - like ringing someone else and they can decide whether to answer or not