The Constant and the Conditional
Sound is constant.
Even if you close your ears with your fingers, you will hear blood moving through your veins and arteries. You will hear your finger joints making micro-movements you would otherwise never notice. You will hear your breath. All of these sounds that you never hear otherwise will become very loud. And if there are loud sounds around you, you will still hear them, although they'll be muffled behind the foreground sounds of your own body.
Light is also constant.
Even when you close your eyes, you will see light filtering red through the blood in your eyelids. But you will also notice that your awareness of the sounds around you increases. Close your eyes, and sound moves into the foreground of your awareness.
Sight is conditional.
If you are in total darkness, you will see nothing. If you choose to "look away" from something, you will stop seeing it.
Hearing is constant.
Whether your ears are open or closed with ear plugs or fingers, you will hear something. And, unless a sound is rather quiet, you won't be able to block it out with earplugs or fingers. You can't "hear away," but you can use your mind to redirect your attention to other stimuli.
Listening is conditional.
If we define listening as hearing combined with attention, we have some choice in which sounds filter into our awareness. We may even choose to bring quieter sounds into the foreground of our awareness, even while loud sounds dominate the actual foreground of our soundscape. And thus, we compose our perception of the world.
And yet, the world is what it is:
Light waves. Sound waves. Particles. Mysterious nothingness. Wonder. Love.