Pressure matching with optimized target phase for personal sound zone systems

Pressure matching (PM) is an advanced digital signal processing technique aimed at designing loudspeaker filters to achieve a target acoustic field in a desired sound region. This enables to establish personal sound zones (PSZs) in a desired environment. The target sound field is chosen during the design stage and influences the performance of the system in terms of acoustic contrast (AC) between bright and dark zones, as well as fidelity of the reproduced audio. The sound regions are represented by groups of control points (microphones) properly placed in the considered environment. With more than one control point in the bright region, the same target sound field is usually considered for all the microphones. This paper investigates the optimization of the phase of the target acoustic field required by the PM algorithm in terms of AC. The achievable performance is analyzed in a realistic automotive environment with two sound zones and two control points per zone. The numerical results show a potential improvement of the achievable AC at the cost of some spatial effects and possibly non constant group delay in the reproduced sound, which should nonetheless be tolerable in voice applications.