If you sharpen your listening, you can sharpen your vision. Try this: pick a sound to focus–the train passing, a nearby conversation, birds chirping–and you'll feel start feeling more observant too.
You may notice how the light bounces off the train's windows, the talkative woman's curly red hair or untied shoe, or the health of tree limb hosting a bird's nest.
The art of noticing starts with your ears and expands to other sensory areas. When you hone in on the sonic waves, everything else becomes transparent–it's like watching an IMAX movie.
Listening is seeing on purpose. If you listen to your breath during mindfulness meditation, your mind calms down and creates a quiet zone for focus. Silence is a great canvass for your thoughts.
If you use your ears, your brain seems to work as well. Using one of the senses triggers the whole system like walking does in helping jog the mind. Make sense of the world, several senses at a time.