4) Can the really very cheap microphone fitted to such things
differentiate between the speech or music etc from the TV's own speakers
just a few inches from it and pick up intelligible speech from the other
side of the room?

Yes easily - especially if you know what is being played on the speaker
at the time - its a basic digital echo cancellation technique to excise
the transmitted signal from the received one.

As the microphone was intended to receive spoken commands while the
set is playing normally, I would imagine this separation will occur
natively.

If the spooks need a clean copy of the programme material in order to
do the subtraction with greater accuracy, that won't pose a problem
either.


--

Graham.
%Profound_observation%