I call it ‘selective hearing’ OR ‘peripheral hearing’.
When I copied High Speed Morse, I was able to carry on a conversation, listen to music OR tune out everything else around me.
Later in life, I had one of the first Mobile Phones in my vehicle (3000 grand for my first), a CB radio, a company radio and the AM/FM.
I tended to have them all on and would turn the volume up on whatever ‘interested’ me at the time.
Since I seldom had a passenger, the few times someone would get in everything was so loud to THEM it was ‘annoying’ but I considered it normal.
Guess part of it was due to my tinnitus and using white out methods but it is easy to ‘zonk in and out’ ...
HOWEVER, while aboard ship I could sleep through the sounds etc of NORMALACY like if I was sleeping in during the day and a scheduled drill was set off and the ‘alarm’ went off, I would normally sleep through it.
BUT
If the ‘alarm’ went off and I wasn’t expecting it my feet would be ‘on the deck’ by the time the alert was finished.
That’s another interesting aspect of not hearing, and in your example it’s by choice.
If you have to sleep with noise around, you learn to do it. You tune everything out and sleep. At first it isn’t easy, but you get used to it.
It will be interesting of others come up with more good examples.
“When I copied High Speed Morse, I was able to carry on a conversation, listen to music OR tune out everything else around me.”
I could never do that. I got comfortable enough where I could lag a group or two behind, but that was about it. I knew guys who could keep track of two “conversations” at once, but I never got that good.