This sort of interference is reduced by the fact the two wires are
*twisted* inside the cable which reverses the phase of any hum signal picked
up every inch or so along the line and hence cancels it out. Where multiple
twisted pairs are used in the same cable the twisting reduces crosstalk in
the same way as above.

Twisting puts NOTHING out of phase. Twisting assures that both wires
are introduced the same noise energy amplitude, so that is can be
properly canceled out by the differential input. Twisting improves CMR
because the noise signal is more uniform.



........... Phil