Investigating the effect of arrival time of diffuse reflections on listener envelopment

Abstract

Listener Envelopment (LEV) is a quality of diffuse sound fields, and a highly sought after attribute of performance venues. However, the ability for an enclosure to achieve ideal, diffuse sound field is often difficult, and varies from space to space. Thus, a rigid transition time between early and late energy is an insufficient way of evaluating LEV. Current theories on listener envelopment focus on the arrival time of the reflections within the impulse response, but typically disregard the diffusivity of these reflections, building on the fact that the impulse response generally becomes more diffuse over time. An alternative model is proposed, where the listener envelopment is determined by both the diffusivity and the arrival time of reflections. The model disregards the current 80-ms criterion and also allows reflections earlier then this to contribute to LEV. A 64-channel wave field synthesis system is used to perceptually evaluate the effects of spatially and temporally diffuse sound components as a function of arrival time.