Robust Acoustic Contrast Control with Reduced In-situ Measurement by Acoustic Modelling

Personal audio systems generate a local sound field for a listener while attenuating the sound energy at pre-defined quiet zones. In practice, system performance is sensitive to errors in the acoustic transfer functions between the sources and the zones. Regularization is commonly used to improve robustness, however, selecting a regularization parameter is not always straightforward. In this paper, a design framework for robust reproduction is proposed, combining transfer function and error modelling. The framework allows a physical perspective on the regularization required for a system, based on the bound of assumed additive or multiplicative errors, which is obtained by acoustic modelling. Acoustic contrast control is separately combined with worst-case and probability-model optimization, exploiting limited knowledge of the potential error distribution. Monte-Carlo simulations show that these approaches give increased system robustness compared to the state of the art approaches for regularization parameter estimation, and experimental results verify that robust sound zone control is achieved in the presence of loudspeaker gain errors. Furthermore, by applying the proposed framework, in-situ transfer function measurements were reduced to a single measurement per loudspeaker, per zone, with limited acoustic contrast degradation of less than 2 dB over 100–3000 Hz compared to the fully measured regularized case.