Using a linear microphone array to evaluate inhomogeneous sound-fields of recreated enclosures

Abstract

Auditory Virtual Environments (AVE) typically recreate the sound at a specific listener position. Extended loudspeaker-based systems typically use the rich capabilities to enlarge the sweet spot, so a broader audience can experience the sound from the same virtual listener position. An alternative approach is taken with Rensselaer's Collaborative-Research Augmented Immersive Virtual Environment Laboratory (CRAIVE-Lab). Using 128 horizontally-arranged loudspeakers, inhomogeneous sound fields are produced over a user area of 10x12 sqm, recreating the sound of acoustical enclosures using a ray-tracing method. A linear microphone array, consisting of 40 omnidirectional microphones, spaced 15 cm apart, is used to measure the fidelity of the reproduced inhomogeneous sound fields. This is accomplished by comparing the spatial room impulse responses measured in the CRAIVE-Lab to those generated synthetically (or computationally). The arrival times of direct sound and reflections are compared for both simulation methods. The analysis focuses on the spatial properties of the arriving wave fronts, including the direction of arrival and curvature, to determine the degree of accuracy to which the inhomogeneous properties of the sound field are reproduced.