I don't mean clinically or even functionally. I suspect it is more ontologically. She has willed herself to not hear anything she's not interested in.
Maybe it's a teen phenomenon; however, I think it's more of a human condition.
We're all a bit ontologically deaf. While we may physically hear what someone says to us, do we really listen? According to neuroscientists, we don't. We only really pick up what we're filtering for.
The brain is constantly being bombarded with sensory input from both internal and external sources. From the beating of your heart, to blinking, pumping blood or breathing, your brain is picking up commands from all over your body. In addition, it picks up temperature changes, wind movements, sounds, sights, smells and every bit of external sensory action around you. You'd actually go mad if you were consciously aware of everything your brain picked up.
Can you imagine sitting in a meeting and hearing the constant chatter of commands from your body demanding action from your brain?
So, your clever brain filters all that unwanted noise out. Even the stuff you maybe should hear.
How can you really listen? Open your mind.
Notice that you have filters (we all do) and put them aside. That person you consider to be a jerk? Remember that it's a filter you have in place based on a decision from the past and set it aside. Really listen to them and you may learn something new. Maybe they're not such a jerk after all- just someone with a different world view.
We each have a unique view of the world, with our own values, priorities and needs. When we find people who match some or most of our ideals, we experience connection and are readily able and willing to hear what they have to say.
It takes a bit more effort with people who have a conflicting world view.
But, it's worth the effort. Go ahead and listen. You might learn something new.