What difference can an FM make?

I'm always interested in how things sound for LIly.  

This page contains recordings of speech through a Comtek FM system in quiet and in noise, through the FM (on the lapel of the speaker) and/or environmental (on the body of the listener) microphones, at a distance of three and twelve feet from the listener. Multi-talker babble speech noise was presented from behind the listener at a level of about 60 dBA.

It is not clear if these recordings are through an additional listening device like a hearing aid or cochlear implant, but the differences are still facinating.