The experimental design included three conditions in which the sounds produced by tapping with one's hand on a surface were spatially manipulated. Zero Distance (0D): the tapping sound originated at the tapping location; Double Distance (2D): the sound originated at double the distance to the tapping location; and Quadruple Distance (4D): the sound originated at four times the distance to the tapping location. Participants were instructed to tap at each marked point for ten times, with a frequency of 1 Hz, starting from the point marked in front of them (Figure 1A).We assessed the effects of the different audio-tactile 'tapping' conditions on the represented length

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While rotating visual and auditory stimuli have long been known to elicit self-motion illusions ("circular vection"), audiovisual interactions have hardly been investigated. Here, two experiments investigated whether visually induced circular vection can be enhanced by concurrently rotating auditory cues that match visual landmarks (e.g., a fountain sound). Participants sat behind a curved projection screen displaying rotating panoramic renderings of a market place. Apart from a no-sound condition, headphone-based auditory stimuli consisted of mono sound, ambient sound, or low-/high-spatial resolution auralizations using generic head-related transfer functions (HRTFs). While merely adding nonrotating (mono or ambient) sound showed no effects, moving sound stimuli facilitated both vection and presence in the virtual environment. This spatialization benefit was maximal for a medium (20 • × 15 • ) FOV, reduced for a larger (54 • × 45 • ) FOV and unexpectedly absent for the smallest (10 • × 7.5 • ) FOV. Increasing auralization spatial fidelity (from low, comparable to five-channel home theatre systems, to high, 5 • resolution) provided no further benefit, suggesting a ceiling effect. In conclusion, both self-motion perception and presence can benefit from adding moving auditory stimuli. This has important implications both for multimodal cue integration theories and the applied challenge of building affordable yet effective motion simulators.

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In order to survive in a complex environment, inhabited by potentially threatening and noxious objects or living beings, we need to constantly monitor our surrounding space, especially in the vicinity of our body. Such a space has been commonly referred to as one's 'peripersonal space' (PPS). In this study we investigated whether emotion-inducing approaching sound sources impact the boundaries of PPS. Previous studies have indeed showed that the boundaries of PPS are not fixed but modulate according to properties of stimuli in the surrounding environment. In Experiment 1, participants performed a simple tactile detection task of targets presented to their right hand. Concurrently, they were presented with intensity-changing task-irrelevant artificial sound sources perceived as approaching toward their body. The physical properties of the sound elicited emotional responses of either neutral or negative valence. Results showed larger PPS when the approaching stimulus had negative as compared to neutral emotional valence. In Experiment 2, we used ecological sounds which content (i.e., psychological associations to the sound producing source), rather than physical properties, elicited emotional responses of negative, positive or neutral valence. In agreement with results from experiment 1, we found larger PPS when the approaching stimuli had negative emotional valence as compared to both neutral and positive ones. Results are discussed within the theoretical framework that conceives PPS as a safety zone around one's body.

Research has shown the existence of perceptual and neural bias toward sounds perceived as sources approaching versus receding a listener. It has been suggested that a greater biological salience of approaching auditory sources may account for these effects. In addition, these effects may hold only for those sources critical for our survival. In the present study, we bring support to these hypotheses by quantifying the emotional responses to different sounds with changing intensity patterns. In 2 experiments, participants were exposed to artificial and natural sounds simulating approaching or receding sources. The auditory-induced emotional effect was reflected in the performance of participants in an emotion-related behavioral task, their self-reported emotional experience, and their physiology (electrodermal activity and facial electromyography). The results of this study suggest that approaching unpleasant sound sources evoke more intense emotional responses in listeners than receding ones, whereas such an effect of perceived sound motion does not exist for pleasant or neutral sound sources. The emotional significance attributed to the sound source itself, the loudness of the sound, and loudness change duration seem to be relevant factors in this disparity.

When people hear a sound (a "sound object" or a "sound event") the perceived auditory space around them might modulate their emotional responses to it. Spaces can affect both the acoustic properties of the sound event itself and may also impose boundaries to the actions one can take with respect to this event. Virtual acoustic rooms of different sizes were used in a subjective and psychophysiological experiment that evaluated the influence of the auditory space perception on emotional responses to various sound sources. Participants (N = 20) were exposed to acoustic spaces with sound source positions and room acoustic properties varying across the experimental conditions. The results suggest that, overall, small rooms were considered more pleasant, calmer, and safer than big rooms, although this effect of size seems to disappear when listening to threatening sound sources. Sounds heard behind the listeners tended to be more arousing, and elicited larger physiological changes than sources in front of the listeners. These effects were more pronounced for natural, compared to artificial, sound sources, as confirmed by subjective and physiological measures.