Why is it that when I'm in a completely silent room, I can hear this constant noise from inside my ear drums/head? I would describe the noise as a never-ending high frequency beep. Also, I don't know if this has anything to do with it, but I am never used to being in a space that doesn't have at least a little background noise. 


Is this (the sound) just a normal thing? Or is there something that could be wrong?