There's a new ringtone specifically for teenagers. It uses very high frequencies and so can't be heard by older people as the ability to detect these very high frequencies is something which deteriorates with age.
There was an item about it on the evening news, during which children and adults were interviewed and asked if they could detect the ringtone. The children were able to hear it loud and clear, the adults weren't.
This, I thought, is annoying - another of these age things! So I turned the TV volume up, pressed my ear to the speaker and listened intently............
"Yes, I can hear it," I announced to my sceptic audience of one.
"I can definitely hear it..........I think...................I can, I can, really!"
(Runs in the family, you know, it's in the genes, good hearing. Can hear a pin drop, I can!)