A. Every motor vehicle when operated upon a highway shall be equipped with a horn in good working order and capable of emitting sound audible under normal conditions from a distance of not less than two hundred feet (200'), but no horn or other warning device shall emit an unreasonably loud or harsh sound or a whistle. The driver of a motor vehicle shall, when reasonably necessary to insure safe operation, give audible warning with his horn but shall not otherwise use such horn when upon a highway.
B. No vehicle shall be equipped with nor shall any person use upon a vehicle any siren, whistle or bell, except as otherwise permitted in this subsection. Any authorized emergency vehicle as defined in this Title may be equipped with a siren, whistle or bell capable of emitting sound audible under normal conditions from a distance of not less than five hundred feet (500'), but such siren, whistle or bell shall not be used except when such vehicle is operated in response to an emergency call or in the immediate pursuit of an actual or suspected violator of the law, in either of which events the driver of such vehicle shall sound such siren, whistle or bell when necessary to warn pedestrians and other drivers of the approach thereof. (1976 Code §19-218)