Automotive horns are a significant source of urban noise pollution. While automotive horns, including truck horns, can be useful signal devices in an emergency situation, many drivers use the horn habitually to express minor annoyance and anger, for social purposes, and to intimidate other drivers. In response to the noise pollution attributable to automotive horns, some states and municipalities have passed legislation penalizing unnecessary horn use. Enforcement of such legislation is impractical since a police officer is required to identify the vehicle from which the sound originated, determine whether use of the horn was necessary, and then stop the vehicle to issue a citation. In New York City, for example, there are posted notices stating a $350 fine for horn honking, yet one may readily observe that such signs have no discernible effect on driver behavior. The system of the present invention may find immediate application among operators of fleets of vehicles. For example, a taxi, limousine, bus, utility, courier or trucking company may employ the system to identify drivers of its vehicles who use the horn excessively, where "excessive" may be defined as exceeding a predetermined rate of horn use versus distance or time (e.g. uses/mile, uses/hour, etc.). Rental fleet operators may also audit horn use upon "check in" of rented vehicles, in order to assess charges for potential citations that may have issued during the rental term of the vehicle. Furthermore, the audit interface may be accessed by a law enforcement authority, such as the local motor vehicle licensing authority, in order to audit horn use during regular inspection of the vehicle, and to assess a charge or fine based upon the number of horn uses during a predetermined time period, distance driven, or in excess of a predetermined allowance of horn uses.