An Acoustic Design Optimization Technique for Automobile Audio Systems

The automobile audio system is designed to operate in a rather confined space of the passenger cabin. Designing a sound system which will produce the best sound quality within the passenger compartment requires several factors to be considered, such as the positioning of the speakers, the damping introduced by the walls, the size and shape of the enclosure, etc. Finite element modeling of the cabin is an effective means in the response evaluation of the audio systems. The finite element modeling process combined with optimization techniques, however, makes this design evaluation process even more efficient in determining the optimum conditions for a speaker system inside the automobile passenger cabin.

A typical automobile passenger compartment has been considered in this paper to demonstrate the application of an optimization technique to the acoustic design of the audio system. The air inside the cabin enclosure has been modeled using the acoustic fluid element of the ANSYS® program, while the walls were assumed to be rigid surfaces. For a given location of the speakers in the automobile passenger cabin, the orientation of the speakers and the damping of enclosure walls have been varied in an attempt to obtain a flat sound level response over a frequency band in the audio range. The objective function of the design is the difference between the maximum and minimum response sound pressure level, Δ(SPL), at a given location. This location has been chosen to represent the position of the ears of a listener in the front seats of the cabin.