Design of a Loudspeaker Array for Personal Audio in a Car Cabin

Abstract

With an increasing interest in personal audio systems, the car cabin is an important environment in which to generate different audio programs in different regions, without the use of headphones. Two algorithms, acoustic contrast control and the least squares method, are considered for producing two independent listening zones, one zone including the front passengers and the other including the rear passengers. The generation of an acceptable acoustic contrast between the front and rear zones, using an array of four standard audio loudspeakers, is limited to relatively low frequencies. In order to provide acceptable control over a larger audio bandwidth, a loudspeaker array mounted on the ceiling of a car cabin is investigated in this paper. A selection process for the configuration of the source array is described. Free field simulations are used to calculate the response of the source array and investigate the performance of the two control algorithms. Since the performance of the least squares method is dependent on the chosen target sound pressures, a method for selecting the target sound pressures is also proposed. Finally, the proposed loudspeaker array is implemented in a real car and the measured results are found to be similar to those predicted from the simulations.