Is there any device in the market that allows a person to speak at any volume, but the sound remains confined/enclosed in the area of surroundings of the mouth or face. The idea is to work in places with high restriction of sound levels, and be able to record the sound, not necessarily wireless.
There's a product called ISOVOX 2 that surrounds the head to be portable to record in any environment:
You might want to check that out. Be warned though, it's quite expensive!