Vibrotactile threshold for hairy skin and its transformation into equivalent bone-conduction loss for the mastoid.

Vibrotactile thresholds for the glabrous skin of the hand and for the hairy skin of the arm are investigated as a function of frequency in the range from 40 to 2 000 Hz, using a heavy vibrator. These thresholds are expressed as equivalent bone-conduction loss and compared with vibrotactile thresholds determined with bone vibrators on the arm and mastoid for normally hearing and severely hearing-impaired subjects. The results are used to predict the vibrotactile threshold of the hairy skin of the mastoid under conditions of severe hearing impairment and deafness. The frequency characteristics of a number of vibrators are discussed with respect to their suitability for skin stimulation.