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Mapping Monophonic MIDI Tracks to Vibrotactile Stimuli Using Tactile Illusions

2022 , Remache Vinueza, Byron , Trujillo-León A. , Clim M.-A. , Sarmiento-Ortiz F. , Topon-Visarrea L. , Jensenius A.R. , Vidal-Verdú F.

In this project, we propose an algorithm to convert musical features and structures extracted from monophonic MIDI files to tactile illusions. Mapping music to vibrotactile stimuli is a challenging process since the perceptible frequency range of the skin is lower than that of the auditory system, which may cause the loss of some musical features. Moreover, current proposed models do not warrant the correspondence between the emotional response to music and the vibrotactile version of it. We propose to use tactile illusions as an additional resource to convey more meaningful vibrotactile stimuli. Tactile illusions enable us to add dynamics to vibrotactile stimuli in the form of movement, changes of direction, and localization. The suggested algorithm converts monophonic MIDI files into arrangements of two tactile illusions: “phantom motion” and “funneling”. The validation of the rendered material consisted of presenting the audio rendered from MIDI files to participants and then adding the vibrotactile component to it. The arrangement of tactile illusions was also evaluated alone. Results suggest that the arrangement of tactile illusions evokes more positive emotions than negative ones. This arrangement was also perceived as more agreeable and stimulating than the original audio. Although musical features such as rhythm, tempo, and melody were mostly recognized in the arrangement of tactile illusions, it provoked a different emotional response from that of the original audio. © 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG.

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Design and Implementation of a Wastewater Heat Recovery System Prototype for Electric Showers in Quito-Ecuador

2020 , Remache Vinueza, Byron , Calderón G.E. , Zapata, Mireya

A wastewater heat recovery system was designed and implemented in the city of Quito - Ecuador. The prototype consists of adapting a heat exchanger to recover energy from wastewater and preheat the water that enters an electric shower. A temperature control system was designed and adapted to work based on a preset comfort temperature. A procedure for the manufacture of copper U-pipe fittings was developed for the construction of the heat exchanger coil, which consists of freezing water inside the pipe so that when rolled it avoids crushing and excessive loss of the inner diameter. Results show that for an average family of 4 members a reduction of energy consumption by 57% is possible. For the case of Ecuador, a reduction of 56.69 Mt of equivalent CO2 emissions was estimated if the system was implemented across the country. A payback period of 8.35 years was calculated for the initial investment. © 2020, The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG.

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Sensory Substitution in Music: Enhancing Deaf Perception Through Vibrotactile Feedback

2024 , Johann Jadán , Zapata, Mireya , Remache Vinueza, Byron

Music experienced through vibrotactile interfaces is a method of perceiving musical elements through the sense of touch, often involving vibrations. This technology functions by converting audio signals into physical sensations that can be sensed through the skin, typically via a wearable device like a wristband. Beginning with an initial audio file devoid of tactile feedback, the procedure entails altering it through sinusoidal modeling and, if necessary, implementing a Space-Fixed Audio transformation by utilizing the Head-Related Transfer Function (HRTF). In this study, we successfully transformed sound files into tactile stereo vibrations using specialized hardware. This process was rigorously tested and validated through experimentation involving ten individuals. Our findings confirm that psychophysical sensations can indeed be perceptible. Notably, the most consistent responses were observed when applying the Vibrato and Tremolo effect, following an HRTF transformation. The Space-Fixed Audio transformation primarily introduced variations in azimuth, covering 360∘ in a clockwise direction. Consequently, this processing led to significant spectral changes, effectively rescaling and compressing the audio’s frequencies into lower equivalents. These modified spectral characteristics were subsequently transmitted through vibrotactile actuators, thereby transforming the essence of sound into a tactile experience. This innovative system creates a sensory replacement approach based on the psychophysical sensations perceived on the skin. It has proven to be exceptionally beneficial, particularly for individuals with hearing impairments who may not perceive music in the same way as individuals with typical hearing abilities.

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Vibrotactile stimulus duration threshold for perception of pulse to vibration transition

2025 , Remache Vinueza, Byron , Andrés Trujillo-León , Fernando Vidal-Verdú

This study investigates the minimum stimulus duration required to perceive the transition from pulse to vibration sensations, a critical parameter for optimizing information transmission via haptic interfaces such as smartphones, tablets, smartwatches, game consoles, and sensory substitution systems. Efficient transmission relies on minimizing stimulus duration, enabling more information to be conveyed in less time. A preliminary experiment established intensity perception thresholds—the minimum vibration intensities detectable—at 40, 80, 150, 250, 300, and 590 Hz, frequencies primarily activating the Pacinian (Rapid Adapting II) psychophysical channel. Subsequently, 35 participants determined the minimum durations needed to perceive the transition from pulse to vibration sensations across this frequency range. Results revealed a consistent minimum duration of approximately 30 ms, contrasting with findings in audition, where shorter durations suffice at higher frequencies, but aligning with prior studies in tactile perception.

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Phantom sensation: Threshold and quality indicators of a tactile illusion of motion

2024 , Remache Vinueza, Byron , Trujillo-León A. , Vidal-Verdú F.

Utilizing a randomized, blind, controlled experiment, and the ascending method of limits, we determined the minimum amplitude of motion at which individuals perceive a tactile illusion called moving phantom sensation, the perceived level of clarity and continuity of motion. Implementing tactile illusions in virtual/augmented reality, sensory substitution systems, and other human–computer interaction technologies results in interfaces with improved resolution, using two vibrating actuators only. The actuators are attached to the skin in different locations to render a moving phantom sensation. The intensity of vibrations increases in one actuator while decreases in the other according to the envelope of the voltage supply signals. This intensity variation creates the illusion of a vibrating point moving between the actuators. We gradually increased the amplitude of motion until the participant reported perceiving the illusion, for eight values of duration of the stimulus from 0.1 to 6.0 s. Participants perceived the illusion at a minimum amplitude of motion of 20%; being 100% the motion from one actuator to the other. The median level of clarity of the perceived illusion at the minimum amplitude of motion was 2 (not so clear). Finally, we found a positive correlation between duration and continuity of motion. © 2024 The Author(s)

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A Comparative Investigation of Cutaneous Rabbit and Funneling Tactile Illusions for Implementation in Vibrotactile Displays

2024 , Remache Vinueza, Byron , Andrés Trujillo-León , Fernando Vidal-Verdú

We designed two psychophysical experiments to compare the cutaneous rabbit tactile illusion with a cutaneous rabbit recreated using sequential funneling tactile illusions. These illusions were rendered between a pair of actuators held with the hands. A tactile illusion is a psychophysical phenomenon that arises when the real stimulus does not match the perceived sensation. Designers exploit tactile illusions to efficiently increase the resolution of vibrotactile displays for human-computer interaction applications. Initially, participants qualitatively compared both rendering methods. Subsequently, individuals reported the upper threshold of the Inter-Stimulus Onset Interval (ISOI) for the cutaneous rabbit and the Time Between Funneling (TBF) illusions of the recreated cutaneous rabbit using funneling, when the illusion broke apart. The primary differences reported between both methods for rendering the cutaneous rabbit illusion were related to the perceived amount of jumps and duration. Overall, funneling performed better at evoking the illusion of a hopping rabbit, while both methods effectively conveyed direction sensations. Finally, the upper ISOI threshold we found for the cutaneous rabbit was consistent with the value reported in the literature, approximately 190 milliseconds, and was surpassed by the TBF of the recreated cutaneous rabbit using funneling