My son also does this. He's 14 and seems to hear fine except when he's at school. 
I suppose it's like related or tied to texting?
The way some words/names are spelled on CC sure look like some texts.
They are multitasking because they cannot concentrate on just one thing these days. Just like the time between commercials has gotten shorter and shorter, attention spans due to TikTok, video games, etc., have dropped. In order to maintain that level of "feel-good" hormone and adrenaline in their system, they must have more than one thing going at the same time... It's really kind of sad when you think about it.