A new objective measure for evaluation of listener envelopment focusing on the spatial balance of reflections

We conducted seven subjective experiments in order to clarify the effects of the arrival direction and spatial distribution of reflections on listener envelopment (LEV). As a result, it became clear that the contribution of a reflection to LEV depends on the arrival direction of other reflections, and that making independent evaluation is not entirely a possibility. For our sound fields, LEV cannot be optimally evaluated with objective measures that weight and integrate individual reflections by the arrival direction like that of lateral energy ratios. It is necessary to consider the mutual effects of these reflections by some means and to quantify their spatial distribution of reflections. Accordingly, we have proposed a spatially balanced center time (SBTs) for quantifying the spatial distribution of reflections using center time TS for each direction, and have demonstrated that it is possible to obtain adequate correlations with the psychological scores of LEV.