Investigation of listener envelopment using spherical microphone array measurements and ambisonics playback

Abstract

An important aspect of overall room impression is listener envelopment (LEV), the sense of being immersed in a sound field. Current LEV objective metrics are primarily based on lateral reflections, typically measured with a figure-of-eight microphone. The purpose of this study was to investigate LEV using measured impulse responses (IRs) taken with an Eigenmike 32-element spherical microphone array as an initial step toward creating a new metric for LEV. The spherical array enables a spatial analysis with higher resolution than traditional methods. Impulse response measurements were made in the Peter Kiewit Concert Hall in Omaha, NE, in several seat positions and hall absorption settings. Auralizations were generated by convolving the measured IRs with anechoic music excerpts and then processing the signals for third-order ambisonics playback. The signals were played over an array consisting of 32 loudspeakers in an anechoic chamber. A subjective study was run in which musically trained listeners rated the LEV of the stimuli. Beamforming techniques were used to analyze the IRs to better understand the spatial and temporal factors that contribute to the perception of envelopment. Results will be presented, which correlate the objective measurements to the subjective ratings. [Work supported by NSF Grant 1302741.]