Md. Code, Transportation § 21–1210

(a) A person may not operate a bicycle, an EPAMD, or a motor scooter on any highway, or on any roadway, while the person is wearing any headset covering both ears.

(b) A person may not operate a bicycle, an EPAMD, or a motor scooter on any highway, or on any roadway, while the person is wearing any earplugs in both ears.

(c) The provisions of this section do not apply to:

(1) Any person wearing personal hearing protectors in the form of custom earplugs or molds that are designed to attenuate injurious noise levels, if the custom plugs or molds are designed in such a manner as to not inhibit the wearer’s ability to hear a siren or horn from an emergency vehicle or a horn from another vehicle;

(2) Any person wearing a prosthetic device used to aid the hard of hearing; or

(3) Any person operating a bicycle on a public bicycle pathway expressly authorized for the use of persons operating bicycles.