Spatial auditory displays for speech communications: A comparison of free-field and virtual acoustic environments

Abstract

The ability of listeners to monitor the simultaneous presentation of multiple speech signals was evaluated in free-field and virtual acoustic environments. Two acoustic environment conditions (free-field and virtual) were combined factorially with two spatial conditions (spatially separated and nonspatially separated), eight simultaneous talker conditions (1, 2, 3, 4, 5, 6, 7, and 8), and two sex of critical speech signal (male and female) to provide 64 experimental conditions. A within-subjects design was used. Participants, four males and four females, were required to detect and identify the presentation of critical speech signals among a background of nonsignal speech events. Speech stimuli consisted of a call sign and a color–number combination contained within a carrier phrase (e.g., ‘‘Ready TIGER go to WHITE ONE now.’’). The USAF Air Force Research Laboratory’s (AFRL) Auditory Localization Facility—a 277-speaker geodesic sphere housed within an anechoic chamber—was used for free-field presentation, and AFRL’s 3-D auditory display generators were employed for virtual presentation. Results indicated that spatial separation of the speech stimuli enhanced performance efficiency of the free field and the virtual conditions. Implications for the design of spatial auditory displays to enhance communication effectiveness and situation awareness are discussed.