Perceptual Matching of Room Acoustics for Auditory Augmented Reality in Small Rooms - Literature Review and Theoretical Framework

Directional reverberation time and the image source method for rectangular parallelepipedal rooms

The image source (IS) method is a commonly used geometrical acoustics simulation technique in room and virtual acoustics. In particular, it has been used in the analysis of room reverberation under different choices of geometry and wall conditions. Under a simple rectangular parallelepipedal geometry, reverberation time is known to be dependent on the direction of arrival of reflections relative to the room axes. In this article, a closed-form expression for the directional energy decay and reverberation time is derived, which is valid in the late response, and may be used in the case of either angle-independent or angle-dependent reflection. The expression reduces to an easily evaluated formula in the case of an omnidirectional energy decay curve (EDC). Various numerical results are presented, including the validation of the closed-form expression against EDCs and late reverberation times drawn directly from the IS method.

Co-Immersion in Audio Augmented Virtuality: The Case Study of a Static and Approximated Late Reverberation Algorithm

In immersive Audio Augmented Reality, a virtual sound source should be indistinguishable from the existing real ones. This property can be evaluated with the co-immersion criterion, which encompasses scenes constituted by arbitrary configurations of real and virtual objects. Thus, we introduce the term Audio Augmented Virtuality (AAV) to describe a fully virtual environment consisting of auditory content captured from the real world, augmented by synthetic sound generation. We propose an experimental design in AAV investigating how simplified late reverberation (LR) affects the co-immersion of a sound source. Participants listened to simultaneous virtual speakers dynamically rendered through spatial Room Impulse Responses, and were asked to detect the presence of an impostor, i.e., a speaker rendered with one of two simplified LR conditions. Detection rates were found to be close to chance level, especially for one condition, suggesting a limited influence on co-immersion of the simplified LR in the evaluated AAV scenes. This methodology can be straightforwardly extended and applied to different acoustics scenes, complexities, i.e., the number of simultaneous speakers, and rendering parameters in order to further investigate the requirements for immersive audio technologies in AAR and AAV applications.

Separate effects of auditory and visual room size on auditorium seat preference: a virtual reality study

Audiovisual integrations and interactions happen everywhere, including in music concerts, where combined visual and auditory perception contributes to overall enjoyment. Thirty-three participants evaluated their overall subjective preference at various seats in four virtual auditoria, which comprised congruent and incongruent auditory and visual renders of two auditoria that differ only in size. Results show no significant difference between participants who completed the experiment in a fully calibrated and standardized laboratory environment and participants who completed remotely using various VR equipment in various environments. Both visual and auditory auditorium size have significant main effects, but no interaction. The larger hall is preferred for both conditions. Audiovisual congruency does not significantly affect preference.

Best Distance Perception in Virtual Audiovisual Environment

Auditory distance perception is important to virtual sound production and is affected by many factors. In order to investigate the effect of the visual cue on auditory distance perception and the best auditory distance perception in the existence of virtual sound source, experiments on the effect of visual cue on distance perception and the best auditory distance perception were conducted, respectively. The results of the first experiment showed that there was no obvious difference between the auditory distance perception in the existence and absence of virtual sound source, but visual cue can decrease the fluctuation of the perception. From the best auditory distance perception experiment, the attenuating SPL of the initial sound signal that made the subjects perceive the best auditory distance in the existence of virtual sound source at the distance of 4m, 6m, 8m, 10m, and 12m was measured, respectively, and compared the difference of attenuating SPL between experiment measurement and theoretical calculation.