It's because you lose the ability to form new abstractions once your neocortex shuts down. The sensory areas begin shutting down quite early (around five) for m

It's because you lose the ability to form new abstractions once your neocortex shuts down. The sensory areas begin shutting down quite early (around five) for most. You can only hear which category the sound belongs to + the error ("accent" in this case) and lack the ability to perceive finer nuances after it happens.