Interactive Vibrotactile Feedback Enhances the Perceived Quality of a Surface for Musical Expression and the Playing Experience.

An advanced multi-touch sensor surface aimed at musical expression was recently equipped by the authors with interactive multi-point localized vibrotactile feedback. Using such interface, a subjective assessment was conducted that measured how the presence and type of vibration affect the perceived quality of the device and various attributes related to the playing experience. Two clearly distinct sound settings each with three vibrotactile feedback strategies were tested. At each trial, the task was to play freely while comparing two related setups which used the same sound setting and differed only in the presence/absence of vibration. Independent of the sound setting, as compared to the respective non-vibrating setups, vibrations conveying frequency and amplitude dynamics cues coherent with the player's gesture and/or sonic feedback had the most positive effect. Vibrotactile feedback especially improved the enjoyment of playing and the perceived potential for musical expressivity.

Vibrotactile Sensitivity in Active Touch: Effect of Pressing Force.

An experiment was conducted to study the effects of force produced by active touch on vibrotactile perceptual thresholds. The task consisted in pressing the fingertip against a flat rigid surface that provided either sinusoidal or broadband vibration. Three force levels were considered, ranging from light touch to hard press. Finger contact areas were measured during the experiment, showing positive correlation with the respective applied forces. Significant effects on thresholds were found for vibration type and force level. Moreover, possibly due to the concurrent effect of large (unconstrained) finger contact areas, active pressing forces, and long duration stimuli, the measured perceptual thresholds are considerably lower than what previously reported in the literature.