You don't want the earphone or earphone
wires to cross the electrode wires if you can
help it.  The electrical signal that "drives" the
earphone is magnetic - the electrode wires
can pick it up.  This is not the worst thing in
the world; the audiologist will recognize it
as a signal artifact at the beginning of the ABR
trace.  However, it is best to avoid it where

It is not necessary to worry about the insert
earphone tubes crossing the electrode wires;
the acoustic signal cannot contaminate the
electrical signal.

If your audiologist uses a circumaural
earphone, rather than insert earphones, it
will be more of a challenge to keep the
electrode wires from coming near the
earphone wires.