Electrovibration is one of the methods by which users can perceive textures. Electrovibration along with vibrotactile stimulus can enhance texture perception. Several studies have already combined electrovibration and vibrotactile stimuli before, however at threshold or suprathreshold. Multi-modal stimuli at threshold had been reported to exhibit tactile masking inherently. Effect of stimuli at subthreshold and the tactile masking have been missing in the literature. In the current study, a psychophysical experiment was conducted to investigate the effect of subthreshold vibrotactile stimulus (SVS) on the perception of electrovibration. The results from the experiment indicate a reduction of electrovibration threshold by 28.52 20-320 Hz) for electrovibration, and the vibrotactile stimulus was maintained 235 Hz. The perception of the combined stimuli was evaluated in a separate experiment using the Likert’s scale. The results showed that the sensation of electrovibration is dominating at 80
Cochlear implants (CIs) allow individuals that can no longer benefit from hearing aids to understand speech with remarkable efficiency. On the other hand, they perform poorly in music perception. Previous research suggest that music experience can be enhanced with the use of other senses such as touch. We present Tickle Tuner, a haptic feedback device suitable for musical training of CI users. The prototype is composed of two high-quality haptic actuators and an external Digital to Analogue Converter (DAC) hosted in a 3D printed enclosure coupled with a smartphone. We describe the design and implementation of the prototype and the analysis of its characteristics. We introduce a test bench for the design of different mappings between sound and vibrations which we assessed with a Melodic Contour Identification (MCI) task. Results from a group of fifteen normal hearing participants using CIs simulation showed significantly higher performance (increase of 26% more correct answers) with haptic feedback than without.
The principle of particle jamming, a physical effect where fluids can be made to change their hardness at will, has many applications in engineering. Previous research has investigated combining this change of hardness with other haptic effects, resulting in a technology that can render vibration, hardness/softness and shape. This paper proceeds to describe the application of this technology to a soft haptic joystick handle for use in interactive games and telerobotics scenarios. Dynamically generated sound waveforms are used to drive vibrations inside the handle, and a microphone records these as they reach the tip of the handle under different jamming conditions. Audio frequency analysis is then used to analyse the behaviour of the resulting vibrations. This analysis shows that vibration is lowest under a strong vacuum, confirming previous observations that increasing the hardness of the particle fluid has the effect of restricting the displacement of the source vibrations. Moreover, frequency of vibration remained broadly stable in both hard and soft states again confirming previous observations. These results, obtained with a fundamentally different haptic device and sound-based instrumentation, necessitate the conclusion that the behaviour of particle jamming controlled vibration is repeatable and controllable regardless of the physical configuration in which it is used.
We present our study on the design and evaluation of sound samples for motion perception in a Virtual Reality (VR) application. In previous study we found our sound samples to be incoherent with the VR visual channel. In current research we designed four new samples and tested them adapting standard subjective evaluation protocols to our needs. Twenty participants participated to the study and rated each animation in Realism, Matching and Plausibility. Significant differences were found among the sounds and discussion rose on the need for realism in VR applications as well as users’ expectation and how it could influence their experience.
The quantization of vibrotactile signals is generally performed in the same way as for audio signals. However, the specificities of the sense of touch may allow other choices for the digitization of vibrotactile signals, in particular on the number of quantization bits. The objective of this paper is to define the minimal number of quantization bits, ensuring an imperceptible digitization to touch. For this, a perceptual study is conducted on a set of signals for several quantization levels. For each signal, the total perceptible harmonic distortion (PTHD), taking into account the vibrotactile thresholds, is defined and calculated. PTHD seems to predict a threshold from which the quantization level of the vibrotactile signals is perceptible. This result was obtained by a perceptive study carried out on 29 subjects from pairwise comparison with vibrotactile signals emitted by an electrodynamic transducer placed in a wristband. If the PTHD of a vibrotactile signal is less than 35 dB, the digitization effect will be imperceptible. This suggests that 8-bit DACs may be sufficient to generate vibrotactile signals without the digitization effects being perceptible.
