Saliency of omnidirectional videos with different audio presentations: Analyses and dataset

There is an increased interest in understanding users' behavior when exploring omnidirectional (360°) videos, especially in the presence of spatial audio. Several studies demonstrate the effect of no, mono, or spatial audio on visual saliency. However, no studies investigate the influence of higher-order (i.e., 4t h- order) Ambisonics on subjective exploration in virtual reality settings. In this work, a between-subjects test design is employed to collect users' exploration data of 360° videos in a free-form viewing scenario using the Varjo XR-3 Head Mounted Display, in the presence of no, mono, and 4th-order Ambisonics audio. Saliency information was captured as head-saliency in terms of the center of a viewport at 50 Hz. For each item, subjects were asked to describe the scene with a short free-verbalization task. Moreover, cybersickness was assessed using the simulator sickness questionnaire at the beginning and at the end of the test. The head-saliency results over time show that with the presence of higher-order Ambisonics audio, subjects concentrate more on the directions sound is coming from. No influence of audio scenario on cybersickness scores was observed. From the analysis of the verbal scene descriptions, it was found that users were attentive to the omnidirectional video, but only for the ‘no audio’ scenario provided minute and insignificant details of the scene objects. The audiovisual saliency dataset is made available following the open science approach already used for the audiovisual scene recordings we previously published. The data is sought to enable training of visual and audiovisual saliency prediction models for interactive experiences.

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