Champ
UHF FM earpiece is the
smallest RF receiver.
It can be used as
in-ear prompter in presentations in front of a big public, in TV shows or in many situations that requires presenting a speech at a dynamic microphone, because this
RF earpiece use a specific radio frequency that will not induce the received signal into the speaking microphone that you are supposed to talk. Only the receivers set on that frequency will receive the signal.
This issue is present at all covert communication systems that uses inductive spy earpieces and accessories. The inductive communication systems use the cellphone as communication carrier.
The microphones used for presentations will receive too the signal from your cellphone, because it also has a loop inside it, just like the spy micro earpiece in your ear. All that you hear in your ear will also be transmitted to the mic and heard by all your listeners.
This is why you have to use as a in-ear prompter a RF earpiece receiver instead of a inductive earpiece.