Measuring speech intelligibility with speech and noise interferers in a loudspeaker-based virtual sound environment

Abstract

Loudspeaker-based virtual sound environments (VSEs) are emerging as a versatile tool for studying human auditory perception. In order to investigate the reproducibility of simple sound scenes, speech reception thresholds (SRTs) were measured with two interferers and in two spatial conditions (co-located and ±30° separated) using the Danish matrix sentence test Dantale II (Wagener et al., 2003). SRTs were measured in a typical listening room and in a VSE consisting of a spherical 64-channel loudspeaker array using simulated room acoustics with mixed-order-Ambisonics (MOA) playback. The speech maskers were taken from the same material as the target (different talker, same sex). The noise maskers had the same long-term spectrum and broadband envelope as the speech interferer but had random phase (Best et al., 2013). The co-located conditions were reproduced comparably in the real room and in the VSE, with both speech and noise interferers. However, spatial separation led to a 3 dB higher benefit in the VSE than in the real room in both interferer conditions. Previous studies using a larger number of sound sources and more reverberation did not show such systematic differences between virtual and reference conditions, suggesting that reproduction errors may be masked in more complex scenes.