Frequency response dependence to vibration sensitivity by pressing

We are interested in estimating whether the harder skin affects the frequency response to vibration sensitivity or not. While there is the difference among individuals, it is well known that the threshold to vibration sensitivity as a function of frequency yields a U-shaped curve that reaches a maximum of sensitivity in the region of 250 Hz as shown in Fig.1. By focusing on this fact, we can evaluate which the vibration sensitivity is changed under the normal condition and the harder skin conditions caused by pressing the proximal phalange of finger forcibly. Through measuring the vibration sensitivity by the psychophysical method, we found that the vibration sensitivity at the frequency of 80 Hz and 120 Hz improves with the statistical significance test (p-value) of below 10 %, but no effect was showed at the frequency of 10 Hz and 30 Hz.