New Scientist reported recently on a strange necklace that will soon be available from Ambient Corporation of Dallas, Texas. It has a package of sensors that pick up electrical impulses around the vocal chords. These signals are used to drive an artificial voice. Effectively, the necklace lets you subvocalize audibly (if that makes any sense) or (equally senselessly) to converse without speaking.
It's actually designed for people who cannot speak normally, but Ambient apparently feels that there's a wider market. It would certainly be helpful in noisy environments---if the collar plugged directly into your phone, the party on the other end would hear only your (artificial) voice, not the noise. Then there are places where talking on the phone isn't (well, shouldn't be) acceptable--theaters, trains, etc. The collar could be a boon to polite society.
I do have a concern, however, and it's around what I guess you'd call "leakage." Here's part of a typical phone conversation, with unspoken thoughts in italics.
"How's it going, Joe?" I wish you'd stop calling me, you psycho.
"Fine, Robin, just fine." Have they fired you yet, dink brain?
You see where I'm going. We often comment silently on what's happening around us, and most of that commentary should probably never be heard. I'm afraid that Ambient's collar will sometimes (unless you're fully in control of your thoughts) let the truth slip out...something that your relationships, whether personal or professional, probably couldn't survive.