Joey wrote in :

Suppose someone visited your office or home and tried to make a voice
recording using a hidden recorder.

If they used a older-style dictation machine based on tape then you
could detect the electromagnetic transmissions from the dictation
machine when it was recording.

But how would you detect if someone was secretly recording with an MP3
player that recorded to flash memory?

Is there some transmission which could be detected?
Perhaps some low power ultra high frequency from chip refresh cycles?


There probably is a little electro magnetic energy leaving the device, but
what frequency would you try to find it on? Other electronic things such
as computers, printers, etc in the office most likely emit far more RF
noise than the MP3 device. It would be hard to find it. Eventually, the
power would run down and the thing would stop recording. Someone would
have to come by again and pick up the recorder. So your best bet is to be
on the lookout for any suspicious recorder placement and pick up activity.

Or just buy as stereo for your office and play it real loud all the time.

Maybe belch and fart a lot too.

SC