Colouration in Local Wave Field Synthesis

Sound field synthesis techniques including wave field synthesis and near-field-compensated higher order ambisonics aim at a physically accurate reproduction of a desired sound field inside an extended listening area. This area is surrounded by loudspeakers individually driven by their respective driving signals. The latter have to be chosen such that the superposition of all emitted sound fields coincides with the desired one. Due to practical limitations, artefacts impair the synthesis accuracy resulting in a perceivable change in timbre. Recently, two approaches to so-called local wave field synthesis were published that enhance the reproduction accuracy in a limited region while allowing stronger artefacts outside. This paper reports on two listening experiments comparing conventional techniques for sound field synthesis with the mentioned approaches. Furthermore, the influence of different parametrizations for local wave field synthesis is investigated. The results show that the enhanced reproduction accuracy in local wave field synthesis leads to a reduction of perceived colouration, if a suitable parametrization is chosen.