Sensory Equivalence Conversion of High-Frequency Vibrotactile Signals using Intensity Segment Modulation Method for Enhancing Audiovisual Experience

摘要

High-frequency vibrations over a wide range can enhance the audiovisual experience. However, they require a high-response actuator and often cause acoustic noise. This study proposes a general conversion method of high-frequency vibrations into lower frequency ones while maintaining the original vibrotactile sensation. We developed the intensity segment modulation (ISM) method, which relies on the intensity-based perception model and the human capacity to detect temporal fluctuations in intensity at less than 100 Hz frequencies. The ISM allows us to convert any high-frequency vibrations (including the human auditory range) into a lower-frequency vibration at 150 – 300 Hz, which is suitable for typical haptic vibrators. The method divides the original signals into time segments in a specific period to match the human temporal resolution. Then, it calculates the intensity of each segment by decomposing the signals. ISM can output an amplitude-modulated waveform with a single carrier frequency. The sensory equivalence experiment showed that harmonic and percussive types vibrations at 400 Hz and 600 Hz were successfully converted into vibrations of 150 – 300 Hz with almost similar sensations or slightly different. The subjective evaluation of two video contents, i.e., a violin player and fireworks, demonstrated that the proposed method could deliver better-augmented reality.