R.I. Gen. Laws § 31-23-8: Horn required.

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′). However, 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 or her horn but shall not otherwise use the horn when upon a highway. Violations of this section are subject to fines enumerated in § 31-41.1-4.