I was using a simple app on my iPhone yesterday (a flashlight app) and there was a button for mute.
I was confused because it seemed as if the button showed that the app was on mute, but sounds were still being played.
I figured out that the button was showing me what would happen if I pressed it. After I pressed it, it muted and the button changed from a speaker with an X through it to a full speaker (illustrating that if I were to press it again, it would become whatever the picture showed)
Is this intuitive? Should the pictures be reversed so the icon depicts what is the current state rather than what the state will become once pressed?