A Fast Method for Measuring Vibrotactile Threshold Profiles Across Frequency

Measuring vibrotactile detection thresholds across frequency is time-consuming because conventional procedures require separate adaptive measurements at each tested frequency. This limitation becomes critical when dense spectral sampling or multiple body locations are needed. Inspired by Békésy audiometry, we developed a rapid tactile screening method in which vibration frequency is swept across a broad range while stimulus level is adjusted from the participant's ongoing responses. In a pilot study with 12 participants, sinusoidal vibrations were delivered with a calibrated handheld piezoelectric stimulator, and threshold tracking was obtained over 40 logarithmically spaced frequencies between 20 and 1000~Hz in less than two minutes. The method recovered the expected main features of vibrotactile sensitivity, including highest fingertip sensitivity around 200--300~Hz, while remaining much faster than conventional point-by-point procedures, which required about 30~minutes. Measurements at the fingertip, wrist, forearm, and lips also revealed distinct threshold profiles across body sites. These preliminary results suggest that sweep-based threshold tracking can provide a practical tool for rapid vibrotactile screening and for future studies of anatomical or clinical differences in tactile sensitivity.