Cost-constrained broadband array design based on optimal spacing

The use of linear electroacoustic arrays for audio acquisition and reproduction is becoming more common in the consumer arena. Such arrays exhibit degraded frequency response behavior at off-broadside angles unless some broadband beamforming scheme is employed. Typical broadband beamformers, however, involve costs and compromises which are prohibitive for low-end deployment. For low-end loudspeaker array applications, it is critical to maximize the far-field broadside magnitude. This requirement implies maximal broadband usage of all of the array elements, which rules out prior approaches and essentially imposes a uniform excitation constraint. We thus consider a cost-effective approach to improving broadband array performance based solely on using optimal interelement spacings. The array configuration is determined by an exhaustive search for element positions on a discrete lattice and optimization of a simple response metric. The search leverages the ability to characterize the far-field response of a linear array via the DFT of the array weighting profile. We show the resulting broadband response improvements and demonstrate use of the algorithm for bandlimited and compound array designs.