Sound zone methods aim to create multiple listening areas within a room, allowing independent playback of different audio content. Achieving this requires a loudspeaker array, multiple microphones per sound zone and a set of control filters, the design of which involves the Room Impulse Responses (RIRs) between loudspeakers and microphones. Under certain acoustic conditions, acquiring these RIRs is possible using very short acquisition times. At lower frequencies, longer wavelengths enable spatial sampling of the sound zones with fewer points, reducing the required number of microphone positions and amount of data to process. This study exploits this characteristic to render and evaluate low-frequency sound zones in two real rooms, with few spatial sampling points. The performance is assessed by objectively evaluating multiple spatial sampling configurations and RIR acquisition times. Furthermore, the systems inherent ability to control sound beyond the sampled regions is evaluated by assessing the sound field over wider areas. For sound zones roughly the size of a human head, satisfactory performance is achieved in low reverberation conditions with at least four microphones, even for RIR acquisition times as short as 150 milliseconds. Conversely, the performance degradation in highly reflective environments cannot be compensated using additional microphones nor longer acquisition times. Finally, reducing these two factors enables faster control filter calculations.
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