(a) The Mayor is authorized where it is necessary to preserve health to establish zones of quiet. Whenever authorized signs are erected indicating a zone of quiet, no person operating a motor vehicle within any such zone shall sound the horn or other warning device of such vehicle except in an emergency.
(b) Except as otherwise provided in this subsection, whoever violates this section is guilty of a minor misdemeanor. If, within one year of the offense, the offender previously has been convicted of or pleaded guilty to one predicate motor vehicle or traffic offense, whoever violates this section is guilty of a misdemeanor of the fourth degree. If, within one year of the offense, the offender previously has been convicted of two or more predicate motor vehicle or traffic offenses, whoever violates this section is guilty of a misdemeanor of the third degree.