From stages to screens, I hide a whole world--a one-way mirror, never touched or held--yet the only way to see outside me is to break me. What am I?

I have a shell, but I do not have a tail. I am often seen in supermarket refrigerators and breakfast menus.

My whispers travel where voices can’t reach. Obscure yet precise, I have secrets to teach. Repeated in patterns, though silent to most. Shapes and sounds, but invisible like a ghost. Everyone here can see my name, yet I remain hidden.

I am related to surprise, but I am not a happy sound. You might yawn when you think of me.

I am located in a town, a city, and throughout the land, but I am not in a lake, sea, river, or ocean. People visit me for visiting others.