just a demonstration on why voice coils have a slit. without it, they make a shorted loop and would take inductance from the coil winding that surrounds it. when the wire is not connected together, the energy has no place to go through the wire to "short" itself and thus, does nothing. but, when the wire (former) is shorted, inductances causes the wire to then be heated by the moving current within the coil.
the more part-
the wire being closed is very similar to the way a shorting ring works. the coil makes a field and part of that is absorbed into the steel around it which is then reflective in an apposing manner. a shorting ring helps give this eddy current field a place to go and be wasted to help keep it from affecting the coil