Metallic RF Click

When two pieces of metal touch near a radio or sensitive audio amplifier a click sound is heard. It is generally not due to static electricity because the effect is immediately repeatable.  The main theory is it is due to the electric fields present in any modern home from all the wiring carrying mains electrical voltage.  The two pieces of metal being in different parts of the field. When the two pieces of metal connect a small current flows as the electric field distorts to a new configuration creating the RF click.

If you take a long loop of copper wire and touch the ends near a radio you hear nothing as no change to the electric field results.