Help with design

Hi,
Please excuse the extreme ignorance of the question I am about to pose.
I am fairly handy, but have little in the way of electronics know-how.

A friend of mine is a children's speech therapist who recently had her
therapy room remodeled. There is a need for the parents who are
observing their children to be able to hear the therapy session. The
parents are outside of the room observing through a one-way mirror.
No one else should be able to hear what is going on in the room
(wireless systems that could be 'overheard' would not be acceptable).
Any equipment in the room should be silent and unobtrusive so as not to
disturb the session.

One idea we had is to have a microphone put in a wall with a grill over
it. From the outside, the parents could perhaps plug headphones into
some kind of jack in the outer wall. Does this sound feasible? What
would it take to make this system work? I presume the microphone would
be attached to an amplifier and that would be wired to the jack.

Any other suggestions?
If you could be as specific as you can with model numbers and suppliers
that would be great.

Thanks for your help and suggestions.

-g

 

Your suggestion is probably the simplest and cheapest to get working but it
might be worth putting the microphone in the center of the room or have
several sockets into which movable microphones could be plugged on cables.

Try speaking to the sound engineer at your local theater or to a company
that installs PA systems and the like.

For info a wireless solution need not be unsecure - it's all a matter of
degree. Wired systems can be "tapped" and the system you propose dosen't
encrypt the data so a tap would be all you need. It's possible to do voice
over IP using palmtop computers and wireless LAN cards with a reasonable
level of security (eg basic encryption) but you would need to do some
research.

This web site might be worth a read (perhaps skip the first paragraph or
two).

http://www.wi-fiplanet.com/tutorials/article.php/2171721

 

Thank you for the suggestions.
A moveable microphone would be good if it could be made unobtrusive

I should have mentioned that the solution should be low cost, as this is
a not-for-profit agency. Many of the renovations being put in place are
being done by family and friends.

The issue of 'tapping' isn't a big one. I just want to make sure that
people with a scanner or walkie talkie (or baby monitor) can't tune in
to the therapy session.
The people that work at the agency are therapists, not
computer/electronic experts, so the system should be as foolproof and
maintenance-free as possible.

Any ideas where one can buy the necessary parts for a simple system?

-g

 

Do their telephones have intercom built in? If so, all you need is a
couple telephones. One in the therapy room with the handset laying on
the desk or table, and another to listen to that phone.

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Take a look at this little cutie! ;-)
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Michael A. Terrell
Central Florida

 

Thanks for the interesting idea.
They seem to have a shortage of most of the electronic conveniences, but
I'll certainly check.

The clients (most of whom are autistic or have other developmental
delays) may have a problem concentrating if there is some unusual 'prop'
in the setting.

-g

 

a need for the parents who are observing their children

As small as microphones are being made these days
(tie-clip mic, cell phone headsets), this should be duck soup.
The hardest part is hiding the wire.
Any amplifier and speaker you can get should complete the package.
Even Radio Shack can do this.

 

You can build a simple telephone intercom with a well filtered 24
volt DC power supply, and an audio choke. Parallel the phones, and
connect the choke in one of the lines to the power supply. Old Western
Electric, or Stromberg Carlson 500 series phones work great, and can be
found for nothing.

--
We now return you to our normally scheduled programming.

Take a look at this little cutie! ;-)
http://home.earthlink.net/~mike.terrell/photos.html

Michael A. Terrell
Central Florida