speech. Everyone has a different voice.
In the Second World War, the British assembled thousands
of so-called interceptors — mostly women — whose job it was
to tune in every day and night to the radio broadcasts of the
various divisions of the German military. The Germans were, of
course, broadcasting in code, so — at least in the early part of
the war — the British couldn’t understand what was being said.
But that didn’t necessarily matter, because before long, just by
listening to the cadence of the transmission, the interceptors
began to pick up on the individual fists of the German
operators, and by doing so, they knew something nearly as
important, which was who was doing the sending. “If you
listened to the same call signs over a certain period, you would
begin to recognize that there were, say, three or four different
operators in that unit, working on a shift system, each with his
own characteristics,” says Nigel West, a British military
historian. “And invariably, quite apart from the text, there
would be the preambles, and the illicit exchanges. How are you
today? How’s the girlfriend? What’s the weather like in
Munich? So you fill out a little card, on which you write down
all that kind of information, and pretty soon you have a kind of
relationship with that person.”