A numerical approach for the analysis of car snail horn performance

A car horn is a safety device present on every type of vehicle as a warning system. Standard CEE-ECE 70/388 gives the minimum performance requirements in terms of the sound emission a car horn must guarantee outside the vehicle. At the same time, car horns with higher performance are required because of increased noise treatment in the engine compartment. With this in mind, the aim of the proposed research is to optimize and maximize the sound emission of commercial car horns. In this paper, an acoustical finite element model is presented and discussed to determine the cavity modes of the snail horn and to predict the sound pressure emitted outside the horn for an acoustical source excitation. After validation of the proposed numerical approach, the actual geometry of the snail was modified in accordance with an optimization scheme using an automated procedure. The objective of the complete procedure is to increase the emitted sound pressure as well as a set of cavity modes that are well coupled with fundamental working frequencies and with the first harmonic characteristic of the electromagnetic horn housing. Several numerical models are presented and validated against experimental tests