California Bicycle Law of the Day: 27400 Wearing Headsets or Earplugs
27400. A person operating a … bicycle may not wear a headset covering, or earplugs in, both ears. While there are several exceptions, the only exceptions generally applicable are as follows:
(d) A person wearing personal hearing protectors in the form of earplugs or molds that are specifically designed to attenuate injurious noise levels. The 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) A person using a prosthetic device that aids the hard of hearing.