How much radius from outer shield for letting the field "breathe" around a power carrying conductor?

Couldn’t the power carrying cables any of them really, be fitted with a external shield that doesn’t congest the signal’s EM field by having simply anough distance?
The field weakens squarely I presume per distance so the question really is, at what radius could it be considered negligible for the audio band?
(For given currents)

@Elk Move to cables please.