Sound zones: On the effect of ambient temperature variations in feed-forward systems

The precondition for realizing personal sound zones, relying on multichannel feed-forward control, is the robustness in the characterization of the sound field inside the control regions. Achieving high separation depends on the ability to accurately estimate the acoustic transfer functions from a set of control loudspeakers to the zones. In this paper, the assessment of ambient temperature variations is based on a front-to-rear scenario at low frequencies in a car cabin. Experimental studies in a production vehicle show significant performance decrease, when the temperature conditions in the playback situation differ from those present during the setup procedure. The main cause of the mismatch in the two sets of acoustic transfer functions is analyzed and potential compensation strategies are discussed accordingly.