Kern Angelika C, Ellermeier Wolfgang
Technical University of Darmstadt, Institute of Psychology, Darmstadt, Germany.
Front Robot AI. 2020 Feb 21;7:20. doi: 10.3389/frobt.2020.00020. eCollection 2020.
For effective virtual realities, "presence," the feeling of "being there" in a virtual environment (VR), is deemed an essential prerequisite. Several studies have assessed the effect of the (non-)availability of auditory stimulation on presence, but due to differences in study design (e.g., virtual realities used, types of sounds included, rendering technologies employed), generalizing the results and estimating the effect of the auditory component is difficult. In two experiments, the influence of an ambient nature soundscape and movement-triggered step sounds were investigated regarding their effects on presence. In each experiment, approximately forty participants walked on a treadmill, thereby strolling through a virtual park environment reproduced via a stereoscopic head-mounted display (HMD), while the acoustical environment was delivered via noise-canceling headphones. In Experiment 1, conditions with the ambient soundscape and the step sounds either present or absent were combined in a 2 × 2 within-subjects design, supplemented with an additional "no-headphones" control condition. For the synchronous playback of step sounds, the probability of a step being taken was estimated by an algorithm using the HMD's sensor data. The results of Experiment 1 show that questionnaire-based measures of presence and realism were influenced by the soundscape but not by the reproduction of steps, which might be confounded with the fact that the perceived synchronicity of the sensor-triggered step sounds was rated rather low. Therefore, in Experiment 2, the step-reproduction algorithm was improved and judged to be more synchronous by participants. Consequently, large and statistically significant effects of both kinds of audio manipulations on perceived presence and realism were observed, with the effect of the soundscape being larger than that of including footstep sounds, possibly due to the remaining imperfections in the reproduction of steps. Including an appropriate soundscape or self-triggered footsteps had differential effects on subscales of presence, in that both affected overall presence and realism, while involvement was improved and distraction reduced by the ambient soundscape only.
对于有效的虚拟现实而言，“临场感”，即在虚拟环境（VR）中“身临其境”的感觉，被视为一项基本前提条件。多项研究评估了听觉刺激的（不）可用性对临场感的影响，但由于研究设计存在差异（例如，所使用的虚拟现实、所包含的声音类型、采用的渲染技术），很难对结果进行归纳总结并估计听觉成分的影响。在两项实验中，研究了自然环境音景和运动触发的脚步声对临场感的影响。在每项实验中，约40名参与者在跑步机上行走，从而漫步于通过立体头戴式显示器（HMD）再现的虚拟公园环境中，同时通过降噪耳机提供声学环境。在实验1中，采用2×2被试内设计，将自然环境音景和脚步声存在或不存在的条件进行组合，并补充了一个额外的“无耳机”对照条件。对于脚步声的同步回放，使用HMD的传感器数据通过算法估计迈出一步的概率。实验1的结果表明，基于问卷的临场感和真实感测量受音景影响，但不受脚步声再现的影响，这可能与传感器触发的脚步声的感知同步性被评定为相当低这一事实有关。因此，在实验2中，改进了脚步声再现算法，参与者认为其同步性更高。结果观察到，这两种音频处理对感知临场感和真实感均产生了巨大且具有统计学意义的影响，音景的影响大于包含脚步声的影响，这可能是由于脚步声再现仍存在瑕疵。包含适当的音景或自我触发的脚步声对临场感子量表有不同影响，即两者都影响整体临场感和真实感，而只有自然环境音景改善了沉浸感并减少了分心。
