> I have an applicaton where I would like to be able to talk to somebody
> (remotely via radio). However I would like nobody around them to hear what
> is being said. Also it should not be noticable that they have any sort of
> hearing device on(e.g headphones).

Does it have to use speech?
eg is some sort of code acceptable?
If so then Morse or similar would allow telemetry to numerous other places
on the body with mechanical or electrical signal transfer.

Can it be visual - creation of a virtual image either within the frame of
spectacles or superimposed on the lense area would be doable. A very small
text image can be focussed on at very short range with suitable diopter
lenses.

How does the signal get to the recipient?
if it must be dome wirelessly then a 2 stage process seems liable to be
needed. First stage is to receiver proper worn somewhere on the body and
second stage is a wireless short range link to the person interface.

You MAY be able to induce audio within the brain at an appropriate location
using suitably strong magnetic signals. Finding a volunteer for testing may
be problematic :-).

I suppose subcutaneous insertion is out ? :-)
This would arguably be the most viable means for non detectable speech
reception. Given the difficulty in finding a reliable Plutonium supplier and
the annoyance of carrying that much shielding you may consider charging
using inductive power transfer. "Can't hear me? Quick - suck this
electromagnetic lozenge".
Or power could be by mechanical means - chew on a piezo disk or small
alternator. ("He seems to chew a lot when he's thinking." )

Back to work !!!


        Russell McMahon

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