27400.  No person operating any motor vehicle or bicycle shall wear
any headset covering, or any earplugs in, both ears.  The prohibition
of this section does not apply to any of the following:
   (a) Persons operating authorized emergency vehicles, as defined in
Section 165.
   (b) Any person engaged in the operation of either special
construction equipment or equipment for use in the maintenance of any
highway.
   (c) Any person engaged in the operation of refuse collection
equipment who is wearing a safety headset or safety earplugs.
   (d) Any person wearing personal hearing protectors in the form of
custom earplugs or molds that are designed to attenuate injurious
noise levels.  The custom plugs or molds shall be designed in a
manner so as to not inhibit the wearer's ability to hear a siren or
horn from an emergency vehicle or a horn from another motor vehicle.

   (e) Any person using a prosthetic device which aids the hard of
hearing.