Tactile Enhancement of Mid-Air Ultrasonic Stimulation by Wrist Vibration: Perceived Intensity and Pattern Recognition

This study investigates methods to enhance the perceived intensity of mid-air ultrasonic tactile stimuli through the perceptual phenomenon of tactile enhancement. By presenting a brief vibrotactile stimulus to the wrist before stimulating the palm with a mid-air ultrasonic stimulus of the same frequency, we demonstrated that the perceived intensity could be increased by up to 1.7 times. A second user study further examined the effectiveness of this method, revealing that recognition of number-patterned mid-air stimuli was significantly improved by 7.8% with the presence of wrist vibration. These findings offer promising directions for improving the usability of mid-air haptic devices using common wearable technology.