Will wrote:
 I am in the process of buying a Shure PGX1/PGX4
transmitter/receiver system
with the intention of using it with an earset microphone, the small, nearly
invisible 'rice grain' style. 
Well, now that you mention it, here is another perspective on this 
technology.  Before making the investment you might want to consider 
all of the implications.
Regards,
Greg McKenzie
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Un-tethered from Reality: Some Thoughts on Wireless Microphones
I have tried using a wireless headset microphone and found the 
experience wanting.  I owned one for several years and used it 
regularly.  I abandoned it for several reasons.  Not primarily 
because of the increased instances of feedback--something I find 
devastating to the sense of safety and community spirit in the 
hall.  And not because of the monetary and environmental cost of 
batteries, the extra trouble of setting up the mike and receiver, the 
complications of switching the mike off and on again to make "off 
mike" comments, or the feeling of being wired and walking around with 
an electronic device attached to my head.  My decision was also not 
primarily based on concerns about exposing myself and others to 
high-frequency electromagnetic radiation--though I recognize that 
some people are very sensitive to the idea of such exposure.
My primary reason for giving up on the wireless headset was because I 
saw that it was interfering with my ability to connect with the 
dancers, musicians, and others in the hall.
Any speaker at a public event needs to be in a position where the 
entire audience can see them.  This is a very basic 
principle.  People naturally prefer to watch someone who is speaking 
to them.  When someone hears a voice hailing them the most natural 
reaction is to turn one's head toward the source of the sound.  It 
can be disconcerting to look toward the sound source and see an empty 
stage.  The natural reaction is to feel a little bit silly, and to 
look around to try to find the source of the voice.  This is a 
relative small matter but keep in mind that there are probably dozens 
of people going through this reaction whenever a speaker is not in 
the spot where the audience is accustomed to seeing them.  That means 
that for at least a few seconds a big part of your audience is 
feeling silly and disconnected.  Those people are not feeling 
confident or relaxed.  They cannot listen carefully to what the 
speaker is saying.
As an aside here I would point out that an "off-stage mike" is 
commonly used in theatre and stagecraft.  Please note, however, that 
the purpose of the "off-stage mike" is always to build suspense and 
tension.  Something that I, personally, try to avoid when calling 
because I want people to feel relaxed and sociable.  The off-stage 
mike is, therefore, usually accompanied with a visual cue (such as a 
spotlight at the edge of the stage during an introduction) to direct 
the audience's attention in the absence of a physical speaker they can see.
I have attended dances where the caller has used a wireless headset 
mike off-stage freely during the evening.  I always found it 
disconcerting to have to look for the caller in the room.  It also 
seemed a bit creepy to think of a live microphone moving around the 
hall without warning.  Callers sometimes use these mikes while 
speaking to individuals or small groups of dancers who are 
confused.  This is unprofessional because it draws the entire hall's 
attention to the confused dancers and exacerbates the situation by 
creating even more tension.
I quickly learned that when using a wireless headset it is the 
speaker's duty to alert the audience whenever they change 
locations--particularly if they move off stage.  I would say 
something like: "Ladies and gentlemen.  Please direct your attention 
to the center of the hall," before stepping off the stage.  This is 
the courteous thing for a speaker to do.  This helped a lot, but it 
also complicated the process of moving away from my regular 
location.  Ultimately I found that the headset mike was more trouble 
than it was worth.
I can see that these headset or "earset" mikes are very appropriate 
for entertainers who dance or move while singing or speaking and, in 
particular, when they have a spotlight to keep the audience cued as 
to their location.  They also work well for instructors who must 
gesture or handle props while talking, such as in demonstrations.  I 
think such mikes are of particular use to exercise instructors such 
as Jazzercise leaders who generally remain in the same location while teaching.
At calling gigs the sound engineer will often offer me a wireless 
mike to use.  My response is that I am happy to use any mike that 
delivers a good range of high-frequency sounds so that my voice can 
be clearly understood.  Wireless mikes are acceptable, as long as 
they are securely fastened to a mike stand where I will leave them 
during the entire dance.
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