Abstract
The topic of sound zone reproduction, whereby listeners sharing an acoustic space can receive personalized audio content, has been researched for a number of years. Recently, a number of sound zone systems have been realized, moving the concept towards becoming a practical reality. Current implementations of sound zone systems have relied upon conventional loudspeaker geometries such as linear and circular arrays. Line arrays may be compact, but do not necessarily give the system the opportunity to compensate for room reflections in real-world environments. Circular arrays give this opportunity, and also give greater flexibility for spatial audio reproduction, but typically require large numbers of loudspeakers in order to reproduce sound zones over an acceptable bandwidth. Therefore, one key area of research standing between the ideal capability and the performance of a physical system is that of establishing the number and location of the loudspeakers comprising the reproduction array. In this study, the topic of loudspeaker configurations was considered for two-zone reproduction, using a circular array of 60 loudspeakers as the candidate set for selection. A numerical search procedure was used to select a number of loudspeakers from the candidate set. The novel objective function driving the search comprised terms relating to the acoustic contrast between the zones, array effort, matrix condition number, and target zone planarity. The performance of the selected sets using acoustic contrast control was measured in an acoustically treated studio. Results demonstrate that the loudspeaker selection process has potential for maximising the contrast over frequency by increasing the minimum contrast over the frequency range 100--4000 Hz. The array effort and target planarity can also be optimised, depending on the formulation of the objective function. Future work should consider greater diversity of candidate locations.