Scent is increasingly used in virtual reality (VR), but it may have unintended effects on the autonomic nervous system (ANS). In this study, we investigated how several-minute scent exposure via practical olfactory displays affects ANS activity, assuming the use of scent in VR applications by conducting three user studies. First, we used the scent of lavender. Second, we used different scents based on personal preference. Third, we again used the scent of lavender but did not control participants’ breathing. We assessed ANS activity and found no significant differences between before and after scent presentation in any of the three conditions. These results suggest that short-term scent exposure does not produce unintended effects on ANS activity.

In recent years, visual information-based performance support systems using keyboard illumination and projected displays have become popular, but in piano playing, it is also important to acquire proprioception of the fingers and motor skills for rhythm. For this reason, it has been pointed out that traditional visual-oriented methods are insufficient for learning somatic sensations such as accurate fingering and arm movement. This study proposes and develops a piano performance support system that combines visual cues (lighted keys), functional electrical stimulation (FES), and a slider mechanism to assist beginners learning the fundamental skills of appropriate fingering, including accurate keystrokes and timing. By inducing finger flexion via FES to aid fingering, rapidly guiding the arm to the correct key position with the slider mechanism, and visually indicating the target keys, the system provides multi-faceted support for piano learners. The proposed system can sufficiently achieve high-speed, precise arm movement and finger actions for pieces at around 80 BPM. Furthermore, in an evaluation experiment with nine participants, both FES-only support and FES combined with the slider significantly reduced fingering error rates compared to conventional “light” cues alone, with the FESslider combination yielding the greatest improvement. Notably, improved fingering was observed even in passages requiring more advanced techniques for beginners, such as “thumb-under” and “finger substitution.”

Left Unilateral Spatial Neglect (USN) is a higher brain dysfunction following right hemisphere damage, characterized by patients’ neglect of left-sided stimuli. Patients struggle to develop insight into their condition, making rehabilitation difficult. Nukui & Ishiai (2023) developed a virtual reality goggle (VRG) system to simulate USN by implementing a mirror-image viewing condition in a line bisection task. This condition generated a full-field view from right visual field information and displayed it, inducing neglect-like bisection performance in healthy participants. This study builds upon their approach by developing “USN Navigator VR,” an immersive VR system, and validating its effectiveness. This method provides insights into pathological visuospatial processing in USN, aiding future research and rehabilitation strategies.

Redirected walking with the gradient gain, a VR locomotion method, enables users to walk in an undulating virtual space even in a at physical environment by setting the slope of the floor in the virtual environment to be different from that in the physical environment without causing discomfort. However, there are limits to the range of the gradient gain that can be presented without causing discomfort stemming from the discrepancy between visual and proprioceptive sensations. Therefore, we proposed redirected walking using electrical stimulation of the Achilles and tibialis anterior muscle tendons, extending the applicable slope range of redirected walking without compromising the natural gait sensation. Electrical stimulation of the ankle tendons affects the proprioceptive sensation and gives the illusion of tilting in the standing posture, expanding the applicable slope range. Through two user studies, we demonstrated that electrical stimulation of the ankle tendons improves the experience of walking on virtual slopes, both uphill and downhill, in terms of the naturalness of gait and the congruency between visual and proprioceptive perceptions. Notably, electrical stimulation of the Achilles tendons significantly improved the naturalness of the walking experience during virtual downhill walking, which has been considered more challenging in previous studies.

Electrode placement is one of the most important parameters in transcutaneous electrical stimulation. However, it is difficult to intuitively identify the optimal electrode placement that can efficiently stimulate a specific tissue because the human body is composed of multiple tissues arranged in a complex structure. To address this challenge, we developed a system that exhaustively searches the results of current simulations performed via the finite element method, thereby identifying the optimal electrical stimulation conditions from a large number of potential electrode placements. In this study, we applied the system to optimize electrode placement for electrical stimulation of tendons in the lower limbs and nerves in the head, and we confirmed the effectivenessof the proposed system.

ALS is a progressive and incurable disease that gradually restricts physical functions while preserving consciousness, thought processes, and auditory functions. This study proposes a BMI-controlled augmented body system as a means for individuals with ALS to externally express their emotions and intentions despite severe physical limitations. Specifically, we co-designed and implemented a BMI-operated robotic arm with an ALS patient, using auditory stimuli to acquire brain potentials, enabling robotic arm control even in the late stages of the ALS. As a result, the user successfully manipulated the robotic arm at his intended timing, facilitating non-verbal communication such as clapping gestures and waving. This paper presents the system, insights gained from its implementation, and discusses future challenges and considerations.

In this study, we investigate the sense of body ownership (SBO) on adding new sensory organs to a user’s avatar in a virtual space. In this paper, we focus on SBO on the additional ears, the third and fourth ears virtually attached behind the neck, and try to induce the sense by 1) changing the volume of the sound source and 2) providing vibrations with vibration motors in response to hand toward the virtual ears (VEs) and the head movements that change VE positions. The results showed that the avatar’s SBO of VEs was enhanced by 1) the correspondence of the auditory and vibration feedback in response to the user’s head direction, and 2) the elevation of feedback in response to the user’s hand placement on the VEs, while 3) the hand placement on the user’s own ears reduced the SBO.

To realistically represent the human voice in six-degree of freedom content, this study experimentally identifies the radiation point of the human voice on the basis of the distance attenuation characteristics. The distance attenuation characteristics of the human voice are measured in an anechoic chamber using a linear microphone array comprising eight microphones. The radiation point of the human voice is estimated by approximating the obtained distance attenuation characteristics using a hyperbola, and it is found to be in front of the lips in centimeter order.