When I was a kid, I accidentally sprayed wasp spray in my eyes, I had to wear a bandage on both eyes for a couple days and one eye for several weeks thereafter.

When I was a kid, I accidentally sprayed wasp spray in my eyes, I had to wear a bandage on both eyes for a couple days and one eye for several weeks thereafter. I have distinct memories of lying in the ambulance with my eyes covered and later in the emergency room hearing the people go by. I didn't know I was practicing passive sonar at the time, but it has since become a hobby of mine to just close my eyes and see what I can ascertain about my surroundings. It's really interesting to see the things you can pick up. If I'm sitting in a hallway, I can usually guess the gender, build, and style of a person walking by. Similarly, I've taken to closing my eyes while walking home, listening to the different cars go by and using it to locate trees. I would recommend exercises like these to everyone - it really helps center you in your surroundings. You get a really good sense of how complex the world around you really is and how much you tend to tune out - either with your headphones or just selective hearing.