# A Review of Recent Literature on Audio-Based Pseudo-Haptics
## 2 The Review
### Visual-Auditory-Based Pseudo-Haptics  
[PERSON] et al. [58] examined menu control using either a 2D panel and a pseudo-haptic interface based on physical metaphors (buttons/knobs, switches, and sliders) in VR using a Leap Motion Controller mounted on an HMD for hand tracking. The 2D menu interface served as a control based on common touchscreen and mobile user interfaces implemented using standard controls without depth. The pseudo-haptic user interface presented a menu control with pseudo-haptic feedback to enhance users' experience when interacting with button, slider, and switch controllers (i.e., pushing a protruding button/knob or pulling a lever) using auditory and visual feedback. A within-subject experiment was conducted to compare the two interfaces with respect to their influence on user experience, workload, sickness, and immersion. Results showed that the pseudo-haptics-user interface was preferred in all aspects. Although 2D menu control interfaces are simple, widely accepted, and familiar to many, given their widespread use in smartphones and desktop computers, the authors conclude that pseudo-haptic-based controls are the better option for VR menu interfaces. [PERSON] et al. [59] created an augmented reality (AR) simulation that enabled 12 participants to experience their own hand burning using only visual and auditory cues. Physiological data (heart rate (HR), and galvanic skin response (GSR) in particular), and responses to a self-reported questionnaire examining the participants' anxiety levels, presence, and immersion were collected. Half of the participants reported that they experienced the heat sensation. Although the anxiety questionnaire results did not  
Figure 2: Visual scene in the pseudo-haptic study of [57]. (**a**) Top view; (**b**) front view. show any significance, participants experienced a significant increase in skin conductance when observing their hand burning in the simulation. Moreover, those who reported experiencing the heat sensation experienced a higher skin conductance response. [PERSON] et al. (2018) compared three modalities (sound (hearing), vibration (touch), and light (vision)) to provide pseudo-haptic information (grasping force) when in contact with an object. They built a prototype of a remote machine and implemented visual-haptic feedback in similar conditions to real-life operation. A loudspeaker and a vibration motor were attached to the gripper control interface, while an LED was attached to the tip of the robot gripper. A study with 20 participants was conducted and involved grasping and carrying objects for one minute using each of the different feedback modalities. The control consisted of no feedback. Results indicated that although all modalities reduced the grasping force compared to the control, light (visual-based pseudo-haptics) achieved the most significant reduction in grasping force, possibly given that participants found the auditory feedback noisy. Despite this, auditory feedback was found to increase information flow to the brain, suggesting an impact on task performance. [PERSON] et al. (2018) conducted a study to investigate the effect of visual and auditory cues on the perception of roughness and stiffness when interacting with virtual objects in active and passive manners. Forty participants were recruited and underwent active-touch and passive-touch tasks with the objects while wearing a mixed-reality (MR) headset. Active touch refers to haptic feedback generated by the participants touching an object, whereas passive touch is the haptic feedback generated by being touched by an object. The active-touch task involved rotating a virtual cylinder to assess roughness perception, while the passive-touch task required sensing the movement of a vibratory cube to evaluate stiffness perception. The study implemented various auditory and visual cues, and the ordering of the required tasks was counterbalanced.