Section 39-21-36 - Horn and warning device1. While being operated upon a highway, every motor vehicle must 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 [60.96 meters], but no horn or other warning device may emit an unreasonably loud or harsh sound or a whistle. Whenever reasonably necessary for safe operation, the driver of a motor vehicle upon a highway shall give audible warning with the vehicle's horn, but may not otherwise use the vehicle's horn while upon a highway.2. No vehicle may be equipped with nor may any person use upon a vehicle any siren, whistle, or bell, except as otherwise permitted in this section.3. Any vehicle may be equipped with a theft alarm signal device which is so arranged that it cannot be used by the driver as an ordinary warning signal.4. Any authorized emergency vehicle 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 [152.4 meters] and of a type approved by the department, but the siren may not be used except when the vehicle is operated in response to an emergency call or in the immediate pursuit of an actual or suspected violator of the law, in which events the driver of the vehicle shall sound the siren when reasonably necessary to warn pedestrians and other drivers of approaching vehicles.