the noise can possibly be from the wiring itself and not from an
appliance. if you have aluminium wires you must tighten the bolts and
screws that they are connected to. these wires deform under the pressure
and become loose over time. then any current draw is drawn through an
arc at that joint. arcing creates noise. copper wires are slightly
different. over years of use they can corrode with that green looking
crud. this oxide can cause arcing at the joint also. plus the copper
crud is a crystalline substance that can cause some crazy rf racket just
by conducting electricity through it. this crud needs to be cleaned off
the wires and screws. both of these conditions also create heat at the
joint and could possibly start a fire, so noisy wiring should be looked
at just for safety sake.