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.

Influence of Piano Key Vibration Level on Players’ Perception and Performance in Piano Playing

In this study, the influence of piano key vibration levels on players’ personal judgment of the instrument quality and on the dynamics and timing of the players’ performance of a music piece excerpt is examined. In an experiment four vibration levels were presented to eleven pianists playing on a digital grand piano with grand piano-like key action. By evaluating the players’ judgment of the instrument quality, strong integration effects of auditory and tactile information were observed. Differences in the sound of the instrument were perceived by the players, when the vibration level in the keys was changed and the results indicate a sound-dependent optimum of the vibration levels. By analyzing the influence of the vibration levels on the timing and dynamics accuracy of the pianists’ musical performances, we could not observe systematic differences that depend on the vibration level.

Evaluation of Piano Key Vibrations Among Different Acoustic Pianos and Relevance to Vibration Sensation

Recent studies suggest that vibration of piano keys affect the perceived quality of the instrument, as well as the dynamic control and timing in piano playing. However, the time signals of piano key vibrations and its physical properties have not been analyzed and compared to the threshold of vibration sensation in a real-life playing situation yet. This study investigates piano key vibrations and explores the diversity of vibrations among different pianos with a laser Doppler vibrometer. A pianist was performing single keystrokes, note sequences, and a music piece excerpt on four concert grand pianos, five grand pianos, and two upright pianos. The measurements showed peak displacement levels up to 80 m and the frequency spectrum of the vibrations is dominated by frequencies lower than 500 Hz. Finally, a frequency weighting filter is introduced to show that vibration displacement time signals exceed the threshold of human vibration sensation for all evaluated instruments, when a note sequence is played in the bass to mid range with a single hand at forte level. The conducted experiments demonstrate that the vibration characteristics vary distinctively among the investigated pianos.

Detection of keyboard vibrations and effects on perceived piano quality

Two experiments were conducted on an upright and a grand piano, both either producing string vibrations or conversely being silent after the initial keypress, while pianists were listening to the feedback from a synthesizer through insulating headphones. In a quality experiment, participants unaware of the silent mode were asked to play freely and then rate the instrument according to a set of attributes and general preference. Participants preferred the vibrating over the silent setup, and preference ratings were associated to auditory attributes of richness and naturalness in the low and middle ranges. Another experiment on the same setup measured the detection of vibrations at the keyboard, while pianists played notes and chords of varying dynamics and duration. Sensitivity to string vibrations was highest in the lowest register and gradually decreased up to note D5. After the percussive transient, the tactile stimuli exhibited spectral peaks of acceleration whose perceptibility was demonstrated by tests conducted in active touch conditions. The two experiments confirm that piano performers perceive vibratory cues of strings mediated by spectral and spatial summations occurring in the Pacinian system in their fingertips, and suggest that such cues play a role in the evaluation of quality of the musical instrument.

Influence of vibrotactile feedback on some perceptual features of violins

This paper investigated how auditory and vibrotactile feedback information is integrated within the context of violin quality evaluation. Fifteen violinists evaluated three violins on four criteria-"Rich Sound," "Loud and Powerful," "Alive and Responsive," and "Pleasure"-during a perceptual experiment. Violinists first evaluated the violins one at a time under three experimental conditions: (1) playing, (2) listening to it (played by a professional player) in an active way by fingering the score on an isolated neck, (3) same as (2) with vibrotactile feedback provided at the isolated neck. Violinists were then asked to evaluate the violins through pairwise comparisons under condition (3): Each violin was paired with itself while the level of vibrations of the isolated neck was either the original one or divided by two. The first part of the experiment demonstrated that Loud and Powerful judgments were affected by the presence of vibrations given that violins were rated louder in condition (3) than in (2). In the second part, violins were rated more positively with original vibration level at the isolated neck than with half the level, for all criteria but Alive and Responsive. Consistently with sensory interaction, the magnitude of the enhancement remained relatively constant across violins.