Invisibility question for all you physicists?

Now I realize that the British have recently created an invisible "shield" around various small objects, and will soon be able to create them around any object of any size or shape. Some say this is impractical because whatever (or whoever) is inside the cloak won't be able to see as well, because the shield would work both ways. Now, I'm only 17 and no scientist, but here is my question: could some type of sonar or other sound wave-oriented means of seeing be possible, as they do not require actually seeing through the cloak? As in, bouncing back images using sonar to be processed in a device INSIDE the cloak? This could be a set of goggles used by the person who "dons" the cloak. Tell me your opinion, and if I'm wrong or not. I am not completely sure about any of the science I've stated, only what I've been taught.